- 05 May, 2020 13 commits
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Aneesh Kumar K.V authored
update kvmppc_hv_handle_set_rc to use find_kvm_nested_guest_pte and find_kvm_secondary_pte Signed-off-by:
Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Signed-off-by:
Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20200505071729.54912-12-aneesh.kumar@linux.ibm.com
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Aneesh Kumar K.V authored
The locking rules for walking nested shadow linux page table is different from process scoped table. Hence add a helper for nested page table walk and also add check whether we are holding the right locks. Signed-off-by:
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Aneesh Kumar K.V authored
The locking rules for walking partition scoped table is different from process scoped table. Hence add a helper for secondary linux page table walk and also add check whether we are holding the right locks. Signed-off-by:
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Aneesh Kumar K.V authored
These functions can get called in realmode. Hence use low level arch_spin_lock which is safe to be called in realmode. Signed-off-by:
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Aneesh Kumar K.V authored
read_user_stack_slow is called with interrupts soft disabled and it copies contents from the page which we find mapped to a specific address. To convert userspace address to pfn, the kernel now uses lockless page table walk. The kernel needs to make sure the pfn value read remains stable and is not released and reused for another process while the contents are read from the page. This can only be achieved by holding a page reference. One of the first approaches I tried was to check the pte value after the kernel copies the contents from the page. But as shown below we can still get it wrong CPU0 CPU1 pte = READ_ONCE(*ptep); pte_clear(pte); put_page(page); page = alloc_page(); memcpy(page_address(page), "secret password", nr); memcpy(buf, kaddr + offset, nb); put_page(page); handle_mm_fault() page = alloc_page(); set_pte(pte, page); if (pte_val(pte) != pte_val(*ptep)) Hence switch to __get_user_pages_fast. Signed-off-by: -
Aneesh Kumar K.V authored
A lockless page table walk should be safe against parallel THP collapse, THP split and madvise(MADV_DONTNEED)/parallel fault. This patch makes sure kernel won't reload the pteval when checking for different conditions. The patch also added a check for pte_present to make sure the kernel is indeed operating on a PTE and not a pointer to level 0 table page. The pfn value we find here can be different from the actual pfn on which machine check happened. This can happen if we raced with a parallel update of the page table. In such a scenario we end up isolating a wrong pfn. But that doesn't have any other side effect. Signed-off-by:
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Aneesh Kumar K.V authored
Don't fetch the pte value using lockless page table walk. Instead use the value from the caller. hash_preload is called with ptl lock held. So it is safe to use the pte_t address directly. Signed-off-by:
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Aneesh Kumar K.V authored
This is only used with init_mm currently. Walking init_mm is much simpler because we don't need to handle concurrent page table like other mm_context Signed-off-by:
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Aneesh Kumar K.V authored
This makes the pte_present check stricter by checking for additional _PAGE_PTE bit. A level 1 pte pointer (THP pte) can be switched to a pointer to level 0 pte page table page by following two operations. 1) THP split. 2) madvise(MADV_DONTNEED) in parallel to page fault. A lockless page table walk need to make sure we can handle such changes gracefully. Signed-off-by:
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Aneesh Kumar K.V authored
If multiple threads in userspace keep changing the protection keys mapping a range, there can be a scenario where kernel takes a key fault but the pkey value found in the siginfo struct is a permissive one. This can confuse the userspace as shown in the below test case. /* use this to control the number of test iterations */ static void pkeyreg_set(int pkey, unsigned long rights) { unsigned long reg, shift; shift = (NR_PKEYS - pkey - 1) * PKEY_BITS_PER_PKEY; asm volatile("mfspr %0, 0xd" : "=r"(reg)); reg &= ~(((unsigned long) PKEY_BITS_MASK) << shift); reg |= (rights & PKEY_BITS_MASK) << shift; asm volatile("mtspr 0xd, %0" : : "r"(reg)); } static unsigned long pkeyreg_get(void) { unsigned long reg; asm volatile("mfspr %0, 0xd" : "=r"(reg)); return reg; } static int sys_pkey_mprotect(void *addr, size_t len, int prot, int pkey) { return syscall(SYS_pkey_mprotect, addr, len, prot, pkey); } static int sys_pkey_alloc(unsigned long flags, unsigned long access_rights) { return syscall(SYS_pkey_alloc, flags, access_rights); } static int sys_pkey_free(int pkey) { return syscall(SYS_pkey_free, pkey); } static int faulting_pkey; static int permissive_pkey; static pthread_barrier_t pkey_set_barrier; static pthread_barrier_t mprotect_barrier; static void pkey_handle_fault(int signum, siginfo_t *sinfo, void *ctx) { unsigned long pkeyreg; /* FIXME: printf is not signal-safe but for the current purpose, it gets the job done. */ printf("pkey: exp = %d, got = %d\n", faulting_pkey, sinfo->si_pkey); fflush(stdout); assert(sinfo->si_code == SEGV_PKUERR); assert(sinfo->si_pkey == faulting_pkey); /* clear pkey permissions to let the faulting instruction continue */ pkeyreg_set(faulting_pkey, 0x0); } static void *do_mprotect_fault(void *p) { unsigned long rights, pkeyreg, pgsize; unsigned int i; void *region; int pkey; srand(time(NULL)); pgsize = sysconf(_SC_PAGESIZE); rights = PKEY_DISABLE_WRITE; region = p; /* allocate key, no permissions */ assert((pkey = sys_pkey_alloc(0, PKEY_DISABLE_ACCESS)) > 0); pkeyreg_set(4, 0x0); /* cache the pkey here as the faulting pkey for future reference in the signal handler */ faulting_pkey = pkey; printf("%s: faulting pkey = %d\n", __func__, faulting_pkey); /* try to allocate, mprotect and free pkeys repeatedly */ for (i = 0; i < NUM_ITERATIONS; i++) { /* sync up with the other thread here */ pthread_barrier_wait(&pkey_set_barrier); /* make sure that the pkey used by the non-faulting thread is made permissive for this thread's context too so that no faults are triggered because it still might have been set to a restrictive value */ // pkeyreg_set(permissive_pkey, 0x0); /* sync up with the other thread here */ pthread_barrier_wait(&mprotect_barrier); /* perform mprotect */ assert(!sys_pkey_mprotect(region, pgsize, PROT_READ | PROT_WRITE, pkey)); /* choose a random byte from the protected region and attempt to write to it, this will generate a fault */ *((char *) region + (rand() % pgsize)) = rand(); /* restore pkey permissions as the signal handler may have cleared the bit out for the sake of continuing */ pkeyreg_set(pkey, PKEY_DISABLE_WRITE); } /* free pkey */ sys_pkey_free(pkey); return NULL; } static void *do_mprotect_nofault(void *p) { unsigned long pgsize; unsigned int i, j; void *region; int pkey; pgsize = sysconf(_SC_PAGESIZE); region = p; /* try to allocate, mprotect and free pkeys repeatedly */ for (i = 0; i < NUM_ITERATIONS; i++) { /* allocate pkey, all permissions */ assert((pkey = sys_pkey_alloc(0, 0)) > 0); permissive_pkey = pkey; /* sync up with the other thread here */ pthread_barrier_wait(&pkey_set_barrier); pthread_barrier_wait(&mprotect_barrier); /* perform mprotect on the common page, no faults will be triggered as this is most permissive */ assert(!sys_pkey_mprotect(region, pgsize, PROT_READ | PROT_WRITE, pkey)); /* free pkey */ assert(!sys_pkey_free(pkey)); } return NULL; } int main(int argc, char **argv) { pthread_t fault_thread, nofault_thread; unsigned long pgsize; struct sigaction act; pthread_attr_t attr; cpu_set_t fault_cpuset, nofault_cpuset; unsigned int i; void *region; /* allocate memory region to protect */ pgsize = sysconf(_SC_PAGESIZE); assert(region = memalign(pgsize, pgsize)); CPU_ZERO(&fault_cpuset); CPU_SET(0, &fault_cpuset); CPU_ZERO(&nofault_cpuset); CPU_SET(8, &nofault_cpuset); assert(!pthread_attr_init(&attr)); /* setup sigsegv signal handler */ act.sa_handler = 0; act.sa_sigaction = pkey_handle_fault; assert(!sigprocmask(SIG_SETMASK, 0, &act.sa_mask)); act.sa_flags = SA_SIGINFO; act.sa_restorer = 0; assert(!sigaction(SIGSEGV, &act, NULL)); /* setup barrier for the two threads */ pthread_barrier_init(&pkey_set_barrier, NULL, 2); pthread_barrier_init(&mprotect_barrier, NULL, 2); /* setup and start threads */ assert(!pthread_create(&fault_thread, &attr, &do_mprotect_fault, region)); assert(!pthread_setaffinity_np(fault_thread, sizeof(cpu_set_t), &fault_cpuset)); assert(!pthread_create(&nofault_thread, &attr, &do_mprotect_nofault, region)); assert(!pthread_setaffinity_np(nofault_thread, sizeof(cpu_set_t), &nofault_cpuset)); /* cleanup */ assert(!pthread_attr_destroy(&attr)); assert(!pthread_join(fault_thread, NULL)); assert(!pthread_join(nofault_thread, NULL)); assert(!pthread_barrier_destroy(&pkey_set_barrier)); assert(!pthread_barrier_destroy(&mprotect_barrier)); free(region); puts("PASS"); return EXIT_SUCCESS; } The above test can result the below failure without this patch. pkey: exp = 3, got = 3 pkey: exp = 3, got = 4 a.out: pkey-siginfo-race.c:100: pkey_handle_fault: Assertion `sinfo->si_pkey == faulting_pkey' failed. Aborted Check for vma access before considering this a key fault. If vma pkey allow access retry the acess again. Test case is written by Sandipan Das <sandipan@linux.ibm.com> hence added SOB from him. Signed-off-by:Sandipan Das <sandipan@linux.ibm.com> Signed-off-by:
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Aneesh Kumar K.V authored
Fetch pkey from vma instead of linux page table. Also document the fact that in some cases the pkey returned in siginfo won't be the same as the one we took keyfault on. Even with linux page table walk, we can end up in a similar scenario. Signed-off-by:
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Aneesh Kumar K.V authored
We will use this in later patch to do tlb flush when clearing pmd entries. Signed-off-by:
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Michael Ellerman authored
This brings in a fix from the kvm-ppc tree that was merged to mainline after rc2, and so isn't in the base of our topic branch. We'd like it in the topic branch because it interacts with patches we plan to carry in this branch.
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- 20 Apr, 2020 1 commit
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Paul Mackerras authored
Since cd758a9b "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT page fault handler", it's been possible in fairly rare circumstances to load a non-present PTE in kvmppc_book3s_hv_page_fault() when running a guest on a POWER8 host. Because that case wasn't checked for, we could misinterpret the non-present PTE as being a cache-inhibited PTE. That could mismatch with the corresponding hash PTE, which would cause the function to fail with -EFAULT a little further down. That would propagate up to the KVM_RUN ioctl() generally causing the KVM userspace (usually qemu) to fall over. This addresses the problem by catching that case and returning to the guest instead. For completeness, this fixes the radix page fault handler in the same way. For radix this didn't cause any obvious misbehaviour, because we ended up putting the non-present PTE into the guest's partition-scoped page tables, leading immediately to another hypervisor data/instruction storage interrupt, which would go through the page fault path again and fix things up. Fixes: cd758a9b "KVM: PPC: Book3S HV: Use __gfn_to_pfn_memslot in HPT page fault handler" Bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=1820402Reported-by:
David Gibson <david@gibson.dropbear.id.au> Tested-by:
Paul Mackerras <paulus@ozlabs.org>
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- 19 Apr, 2020 12 commits
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Linus Torvalds authored
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Brian Geffon authored
When remapping a mapping where a portion of a VMA is remapped into another portion of the VMA it can cause the VMA to become split. During the copy_vma operation the VMA can actually be remerged if it's an anonymous VMA whose pages have not yet been faulted. This isn't normally a problem because at the end of the remap the original portion is unmapped causing it to become split again. However, MREMAP_DONTUNMAP leaves that original portion in place which means that the VMA which was split and then remerged is not actually split at the end of the mremap. This patch fixes a bug where we don't detect that the VMAs got remerged and we end up putting back VM_ACCOUNT on the next mapping which is completely unreleated. When that next mapping is unmapped it results in incorrectly unaccounting for the memory which was never accounted, and eventually we will underflow on the memory comittment. There is also another issue which is similar, we're currently accouting for the number of pages in the new_vma but that's wrong. We need to account for the length of the remap operation as that's all that is being added. If there was a mapping already at that location its comittment would have been adjusted as part of the munmap at the start of the mremap. A really simple repro can be seen in: https://gist.github.com/bgaff/e101ce99da7d9a8c60acc641d07f312c Fixes: e346b381 ("mm/mremap: add MREMAP_DONTUNMAP to mremap()") Reported-by:
syzbot <syzkaller@googlegroups.com> Signed-off-by:
Brian Geffon <bgeffon@google.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/clk/linuxLinus Torvalds authored
Pull clk fixes from Stephen Boyd: "Two build fixes for a couple clk drivers and a fix for the Unisoc serial clk where we want to keep it on for earlycon" * tag 'clk-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/clk/linux: clk: sprd: don't gate uart console clock clk: mmp2: fix link error without mmp2 clk: asm9260: fix __clk_hw_register_fixed_rate_with_accuracy typo
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull x86 and objtool fixes from Thomas Gleixner: "A set of fixes for x86 and objtool: objtool: - Ignore the double UD2 which is emitted in BUG() when CONFIG_UBSAN_TRAP is enabled. - Support clang non-section symbols in objtool ORC dump - Fix switch table detection in .text.unlikely - Make the BP scratch register warning more robust. x86: - Increase microcode maximum patch size for AMD to cope with new CPUs which have a larger patch size. - Fix a crash in the resource control filesystem when the removal of the default resource group is attempted. - Preserve Code and Data Prioritization enabled state accross CPU hotplug. - Update split lock cpu matching to use the new X86_MATCH macros. - Change the split lock enumeration as Intel finaly decided that the IA32_CORE_CAPABILITIES bits are not architectural contrary to what the SDM claims. !@#%$^! - Add Tremont CPU models to the split lock detection cpu match. - Add a missing static attribute to make sparse happy" * tag 'x86-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: x86/split_lock: Add Tremont family CPU models x86/split_lock: Bits in IA32_CORE_CAPABILITIES are not architectural x86/resctrl: Preserve CDP enable over CPU hotplug x86/resctrl: Fix invalid attempt at removing the default resource group x86/split_lock: Update to use X86_MATCH_INTEL_FAM6_MODEL() x86/umip: Make umip_insns static x86/microcode/AMD: Increase microcode PATCH_MAX_SIZE objtool: Make BP scratch register warning more robust objtool: Fix switch table detection in .text.unlikely objtool: Support Clang non-section symbols in ORC generation objtool: Support Clang non-section symbols in ORC dump objtool: Fix CONFIG_UBSAN_TRAP unreachable warnings -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull time namespace fix from Thomas Gleixner: "An update for the proc interface of time namespaces: Use symbolic names instead of clockid numbers. The usability nuisance of numbers was noticed by Michael when polishing the man page" * tag 'timers-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: proc, time/namespace: Show clock symbolic names in /proc/pid/timens_offsets
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull perf tooling fixes and updates from Thomas Gleixner: - Fix the header line of perf stat output for '--metric-only --per-socket' - Fix the python build with clang - The usual tools UAPI header synchronization * tag 'perf-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: tools headers: Synchronize linux/bits.h with the kernel sources tools headers: Adopt verbatim copy of compiletime_assert() from kernel sources tools headers: Update x86's syscall_64.tbl with the kernel sources tools headers UAPI: Sync drm/i915_drm.h with the kernel sources tools headers UAPI: Update tools's copy of drm.h headers tools headers kvm: Sync linux/kvm.h with the kernel sources tools headers UAPI: Sync linux/fscrypt.h with the kernel sources tools include UAPI: Sync linux/vhost.h with the kernel sources tools arch x86: Sync asm/cpufeatures.h with the kernel sources tools headers UAPI: Sync linux/mman.h with the kernel tools headers UAPI: Sync sched.h with the kernel tools headers: Update linux/vdso.h and grab a copy of vdso/const.h perf stat: Fix no metric header if --per-socket and --metric-only set perf python: Check if clang supports -fno-semantic-interposition tools arch x86: Sync the msr-index.h copy with the kernel sources
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull irq fixes from Thomas Gleixner: "A set of fixes/updates for the interrupt subsystem: - Remove setup_irq() and remove_irq(). All users have been converted so remove them before new users surface. - A set of bugfixes for various interrupt chip drivers - Add a few missing static attributes to address sparse warnings" * tag 'irq-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: irqchip/irq-bcm7038-l1: Make bcm7038_l1_of_init() static irqchip/irq-mvebu-icu: Make legacy_bindings static irqchip/meson-gpio: Fix HARDIRQ-safe -> HARDIRQ-unsafe lock order irqchip/sifive-plic: Fix maximum priority threshold value irqchip/ti-sci-inta: Fix processing of masked irqs irqchip/mbigen: Free msi_desc on device teardown irqchip/gic-v4.1: Update effective affinity of virtual SGIs irqchip/gic-v4.1: Add support for VPENDBASER's Dirty+Valid signaling genirq: Remove setup_irq() and remove_irq() -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull scheduler fixes from Thomas Gleixner: "Two fixes for the scheduler: - Work around an uninitialized variable warning where GCC can't figure it out. - Allow 'isolcpus=' to skip unknown subparameters so that older kernels work with the commandline of a newer kernel. Improve the error output while at it" * tag 'sched-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: sched/vtime: Work around an unitialized variable warning sched/isolation: Allow "isolcpus=" to skip unknown sub-parameters -
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tipLinus Torvalds authored
Pull RCU fix from Thomas Gleixner: "A single bugfix for RCU to prevent taking a lock in NMI context" * tag 'core-urgent-2020-04-19' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: rcu: Don't acquire lock in NMI handler in rcu_nmi_enter_common()
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git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4Linus Torvalds authored
Pull ext4 fixes from Ted Ts'o: "Miscellaneous bug fixes and cleanups for ext4, including a fix for generic/388 in data=journal mode, removing some BUG_ON's, and cleaning up some compiler warnings" * tag 'ext4_for_linus_stable' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: ext4: convert BUG_ON's to WARN_ON's in mballoc.c ext4: increase wait time needed before reuse of deleted inode numbers ext4: remove set but not used variable 'es' in ext4_jbd2.c ext4: remove set but not used variable 'es' ext4: do not zeroout extents beyond i_disksize ext4: fix return-value types in several function comments ext4: use non-movable memory for superblock readahead ext4: use matching invalidatepage in ext4_writepage
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git://git.samba.org/sfrench/cifs-2.6Linus Torvalds authored
Pull cifs fixes from Steve French: "Three small smb3 fixes: two debug related (helping network tracing for SMB2 mounts, and the other removing an unintended debug line on signing failures), and one fixing a performance problem with 64K pages" * tag '5.7-rc-smb3-fixes' of git://git.samba.org/sfrench/cifs-2.6: smb3: remove overly noisy debug line in signing errors cifs: improve read performance for page size 64KB & cache=strict & vers=2.1+ cifs: dump the session id and keys also for SMB2 sessions
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Linus Torvalds authored
Merge tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux Pull flexible-array member conversion from Gustavo Silva: "The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] sizeof(flexible-array-member) triggers a warning because flexible array members have incomplete type[1]. There are some instances of code in which the sizeof operator is being incorrectly/erroneously applied to zero-length arrays and the result is zero. Such instances may be hiding some bugs. So, this work (flexible-array member convertions) will also help to get completely rid of those sorts of issues. Notice that all of these patches have been baking in linux-next for quite a while now and, 238 more of these patches have already been merged into 5.7-rc1. There are a couple hundred more of these issues waiting to be addressed in the whole codebase" [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") * tag 'flexible-array-member-5.7-rc2' of git://git.kernel.org/pub/scm/linux/kernel/git/gustavoars/linux: (28 commits) xattr.h: Replace zero-length array with flexible-array member uapi: linux: fiemap.h: Replace zero-length array with flexible-array member uapi: linux: dlm_device.h: Replace zero-length array with flexible-array member tpm_eventlog.h: Replace zero-length array with flexible-array member ti_wilink_st.h: Replace zero-length array with flexible-array member swap.h: Replace zero-length array with flexible-array member skbuff.h: Replace zero-length array with flexible-array member sched: topology.h: Replace zero-length array with flexible-array member rslib.h: Replace zero-length array with flexible-array member rio.h: Replace zero-length array with flexible-array member posix_acl.h: Replace zero-length array with flexible-array member platform_data: wilco-ec.h: Replace zero-length array with flexible-array member memcontrol.h: Replace zero-length array with flexible-array member list_lru.h: Replace zero-length array with flexible-array member lib: cpu_rmap: Replace zero-length array with flexible-array member irq.h: Replace zero-length array with flexible-array member ihex.h: Replace zero-length array with flexible-array member igmp.h: Replace zero-length array with flexible-array member genalloc.h: Replace zero-length array with flexible-array member ethtool.h: Replace zero-length array with flexible-array member ...
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- 18 Apr, 2020 14 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsiLinus Torvalds authored
Pull SCSI fixes from James Bottomley: "Seven fixes: three in target, one on a sg error leg, two in qla2xxx fixing warnings introduced in the last merge window and updating MAINTAINERS and one in hisi_sas fixing a problem introduced by libata" * tag 'scsi-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi: scsi: sg: add sg_remove_request in sg_common_write scsi: target: tcmu: reset_ring should reset TCMU_DEV_BIT_BROKEN scsi: target: fix PR IN / READ FULL STATUS for FC scsi: target: Write NULL to *port_nexus_ptr if no ISID scsi: MAINTAINERS: Update qla2xxx FC-SCSI driver maintainer scsi: qla2xxx: Fix regression warnings scsi: hisi_sas: Fix build error without SATA_HOST
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Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by:Gustavo A. R. Silva <gustavo@embeddedor.com>
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Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by: -
Gustavo A. R. Silva authored
The current codebase makes use of the zero-length array language extension to the C90 standard, but the preferred mechanism to declare variable-length types such as these ones is a flexible array member[1][2], introduced in C99: struct foo { int stuff; struct boo array[]; }; By making use of the mechanism above, we will get a compiler warning in case the flexible array does not occur last in the structure, which will help us prevent some kind of undefined behavior bugs from being inadvertently introduced[3] to the codebase from now on. Also, notice that, dynamic memory allocations won't be affected by this change: "Flexible array members have incomplete type, and so the sizeof operator may not be applied. As a quirk of the original implementation of zero-length arrays, sizeof evaluates to zero."[1] This issue was found with the help of Coccinelle. [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html [2] https://github.com/KSPP/linux/issues/21 [3] commit 76497732 ("cxgb3/l2t: Fix undefined behaviour") Signed-off-by:
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