- 02 Jun, 2020 4 commits
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Vivek Goyal authored
Currently ovl_get_inode() initializes OVL_UPPERDATA flag and for that it has to call ovl_check_metacopy_xattr() and check if metacopy xattr is present or not. yangerkun reported sometimes underlying filesystem might return -EIO and in that case error handling path does not cleanup properly leading to various warnings. Run generic/461 with ext4 upper/lower layer sometimes may trigger the bug as below(linux 4.19): [ 551.001349] overlayfs: failed to get metacopy (-5) [ 551.003464] overlayfs: failed to get inode (-5) [ 551.004243] overlayfs: cleanup of 'd44/fd51' failed (-5) [ 551.004941] overlayfs: failed to get origin (-5) [ 551.005199] ------------[ cut here ]------------ [ 551.006697] WARNING: CPU: 3 PID: 24674 at fs/inode.c:1528 iput+0x33b/0x400 ... [ 551.027219] Call Trace: [ 551.027623] ovl_create_object+0x13f/0x170 [ 551.028268] ovl_create+0x27/0x30 [ 551.028799] path_openat+0x1a35/0x1ea0 [ 551.029377] do_filp_open+0xad/0x160 [ 551.029944] ? vfs_writev+0xe9/0x170 [ 551.030499] ? page_counter_try_charge+0x77/0x120 [ 551.031245] ? __alloc_fd+0x160/0x2a0 [ 551.031832] ? do_sys_open+0x189/0x340 [ 551.032417] ? get_unused_fd_flags+0x34/0x40 [ 551.033081] do_sys_open+0x189/0x340 [ 551.033632] __x64_sys_creat+0x24/0x30 [ 551.034219] do_syscall_64+0xd5/0x430 [ 551.034800] entry_SYSCALL_64_after_hwframe+0x44/0xa9 One solution is to improve error handling and call iget_failed() if error is encountered. Amir thinks that this path is little intricate and there is not real need to check and initialize OVL_UPPERDATA in ovl_get_inode(). Instead caller of ovl_get_inode() can initialize this state. And this will avoid double checking of metacopy xattr lookup in ovl_lookup() and ovl_get_inode(). OVL_UPPERDATA is inode flag. So I was little concerned that initializing it outside ovl_get_inode() might have some races. But this is one way transition. That is once a file has been fully copied up, it can't go back to metacopy file again. And that seems to help avoid races. So as of now I can't see any races w.r.t OVL_UPPERDATA being set wrongly. So move settingof OVL_UPPERDATA inside the callers of ovl_get_inode(). ovl_obtain_alias() already does it. So only two callers now left are ovl_lookup() and ovl_instantiate(). Reported-by:
yangerkun <yangerkun@huawei.com> Suggested-by:
Amir Goldstein <amir73il@gmail.com> Signed-off-by:
Vivek Goyal <vgoyal@redhat.com> Reviewed-by:
Miklos Szeredi <mszeredi@redhat.com>
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Vivek Goyal authored
Currently we use a variable "metacopy" which signifies that dentry could be either uppermetacopy or lowermetacopy. Amir suggested that we can move code around and use d.metacopy in such a way that we don't need lowermetacopy and just can do away with uppermetacopy. So this patch replaces "metacopy" with "uppermetacopy". It also moves some code little higher to keep reading little simpler. Suggested-by:
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Vivek Goyal authored
overlayfs can keep index of copied up files and directories and it seems to serve two primary puroposes. For regular files, it avoids breaking lower hardlinks over copy up. For directories it seems to be used for various error checks. During ovl_lookup(), we lookup for index using lower dentry in many a cases. That lower dentry is called "origin" and following is a summary of current logic. If there is no upperdentry, always lookup for index using lower dentry. For regular files it helps avoiding breaking hard links over copyup and for directories it seems to be just error checks. If there is an upperdentry, then there are 3 possible cases. - For directories, lower dentry is found using two ways. One is regular path based lookup in lower layers and second is using ORIGIN xattr on upper dentry. First verify that path based lookup lower dentry matches the one pointed by upper ORIGIN xattr. If yes, use this verified origin for index lookup. - For regular files (non-metacopy), there is no path based lookup in lower layers as lookup stops once we find upper dentry. So there is no origin verification. If there is ORIGIN xattr present on upper, use that to lookup index otherwise don't. - For regular metacopy files, again lower dentry is found using path based lookup as well as ORIGIN xattr on upper. Path based lookup is continued in this case to find lower data dentry for metacopy upper. So like directories we only use verified origin. If ORIGIN xattr is not present (Either because lower did not support file handles or because this is hardlink copied up with index=off), then don't use path lookup based lower dentry as origin. This is same as regular non-metacopy file case. Suggested-by:
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Amir Goldstein authored
syzbot reported out of bounds memory access from open_by_handle_at() with a crafted file handle that looks like this: { .handle_bytes = 2, .handle_type = OVL_FILEID_V1 } handle_bytes gets rounded down to 0 and we end up calling: ovl_check_fh_len(fh, 0) => ovl_check_fb_len(fh + 3, -3) But fh buffer is only 2 bytes long, so accessing struct ovl_fb at fh + 3 is illegal. Fixes: cbe7fba8 ("ovl: make sure that real fid is 32bit aligned in memory") Reported-and-tested-by: syzbot+61958888b1c60361a791@syzkaller.appspotmail.com Cc: <stable@vger.kernel.org> # v5.5 Signed-off-by:
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- 13 May, 2020 10 commits
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Lubos Dolezel authored
Overlayfs doesn't work well with the fanotify mechanism. Fanotify first probes for the required buffer size for the file handle, but overlayfs currently bails out without passing the size back. That results in errors in the kernel log, such as: [527944.485384] overlayfs: failed to encode file handle (/, err=-75, buflen=0, len=29, type=1) [527944.485386] fanotify: failed to encode fid (fsid=ae521e68.a434d95f, type=255, bytes=0, err=-2) Signed-off-by:
Lubos Dolezel <lubos@dolezel.info> Signed-off-by:
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Chengguang Xu authored
sync_filesystem() does not sync dirty data for readonly filesystem during umount, so before changing to readonly filesystem we should sync dirty data for data integrity. Signed-off-by:
Chengguang Xu <cgxu519@mykernel.net> Signed-off-by:
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Chengguang Xu authored
Share inode with different whiteout files for saving inode and speeding up delete operation. If EMLINK is encountered when linking a shared whiteout, create a new one. In case of any other error, disable sharing for this super block. Note: ofs->whiteout is protected by inode lock on workdir. Signed-off-by:
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Jeffle Xu authored
Since the stacking of regular file operations [1], the overlayfs edition of write_iter() is called when writing regular files. Since then, xattr lookup is needed on every write since file_remove_privs() is called from ovl_write_iter(), which would become the performance bottleneck when writing small chunks of data. In my test case, file_remove_privs() would consume ~15% CPU when running fstime of unixbench (the workload is repeadly writing 1 KB to the same file) [2]. Inherit the SB_NOSEC flag from upperdir. Since then xattr lookup would be done only once on the first write. Unixbench fstime gets a ~20% performance gain with this patch. [1] https://lore.kernel.org/lkml/20180606150905.GC9426@magnolia/T/ [2] https://www.spinics.net/lists/linux-unionfs/msg07153.htmlSigned-off-by:
Jeffle Xu <jefflexu@linux.alibaba.com> Signed-off-by:
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Konstantin Khlebnikov authored
Stacked filesystems like overlayfs has no own writeback, but they have to forward syncfs() requests to backend for keeping data integrity. During global sync() each overlayfs instance calls method ->sync_fs() for backend although it itself is in global list of superblocks too. As a result one syscall sync() could write one superblock several times and send multiple disk barriers. This patch adds flag SB_I_SKIP_SYNC into sb->sb_iflags to avoid that. Reported-by:
Dmitry Monakhov <dmtrmonakhov@yandex-team.ru> Signed-off-by:
Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Reviewed-by:
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Amir Goldstein authored
With index=on, let index dir act as the work dir for copy up and cleanups. This will help implementing whiteout inode sharing. We still create the "work" dir on mount regardless of index=on and it is used to test the features supported by upper fs. One reason is that before the feature tests, we do not know if index could be enabled or not. The reason we do not use "index" directory also as workdir with index=off is because the existence of the "index" directory acts as a simple persistent signal that index was enabled on this filesystem and tools may want to use that signal. Signed-off-by:
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Amir Goldstein authored
With index=on, we copy up lower hardlinks to work dir and move them into index dir. Fix locking to allow work dir and index dir to be the same directory. Signed-off-by:
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Amir Goldstein authored
Teach ovl_indexdir_cleanup() to remove temp directories containing whiteouts to prepare for using index dir instead of work dir for removing merge directories. Signed-off-by:
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Amir Goldstein authored
Similar to the way that a conflict between metacopy=on,redirect_dir=off is resolved, also resolve conflicts between nfs_export=on,index=off and nfs_export=on,metacopy=on. An explicit mount option wins over a default config value. Both explicit mount options result in an error. Without this change the xfstests group overlay/exportfs are skipped if metacopy is enabled by default. Reported-by:
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Dan Carpenter authored
The "buflen" value comes from the user and there is a potential that it could be zero. In do_handle_to_path() we know that "handle->handle_bytes" is non-zero and we do: handle_dwords = handle->handle_bytes >> 2; So values 1-3 become zero. Then in ovl_fh_to_dentry() we do: int len = fh_len << 2; So now len is in the "0,4-128" range and a multiple of 4. But if "buflen" is zero it will try to copy negative bytes when we do the memcpy in ovl_fid_to_fh(). memcpy(&fh->fb, fid, buflen - OVL_FH_WIRE_OFFSET); And that will lead to a crash. Thanks to Amir Goldstein for his help with this patch. Fixes: cbe7fba8 ("ovl: make sure that real fid is 32bit aligned in memory") Signed-off-by:
Dan Carpenter <dan.carpenter@oracle.com> Reviewed-by:
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- 30 Apr, 2020 2 commits
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Vivek Goyal authored
As of now during open(), we don't pass bunch of flags to underlying filesystem. O_TRUNC is one of these. Normally this is not a problem as VFS calls ->setattr() with zero size and underlying filesystem sets file size to 0. But when overlayfs is running on top of virtiofs, it has an optimization where it does not send setattr request to server if dectects that truncation is part of open(O_TRUNC). It assumes that server already zeroed file size as part of open(O_TRUNC). fuse_do_setattr() { if (attr->ia_valid & ATTR_OPEN) { /* * No need to send request to userspace, since actual * truncation has already been done by OPEN. But still * need to truncate page cache. */ } } IOW, fuse expects O_TRUNC to be passed to it as part of open flags. But currently overlayfs does not pass O_TRUNC to underlying filesystem hence fuse/virtiofs breaks. Setup overlayfs on top of virtiofs and following does not zero the file size of a file is either upper only or has already been copied up. fd = open(foo.txt, O_TRUNC | O_WRONLY); There are two ways to fix this. Either pass O_TRUNC to underlying filesystem or clear ATTR_OPEN from attr->ia_valid so that fuse ends up sending a SETATTR request to server. Miklos is concerned that O_TRUNC might have side affects so it is better to clear ATTR_OPEN for now. Hence this patch clears ATTR_OPEN from attr->ia_valid. I found this problem while running unionmount-testsuite. With this patch, unionmount-testsuite passes with overlayfs on top of virtiofs. Signed-off-by: -
Vivek Goyal authored
ovl_setattr() can be passed an attr which has ATTR_FILE set and attr->ia_file is a file pointer to overlay file. This is done in open(O_TRUNC) path. We should either replace with attr->ia_file with underlying file object or clear ATTR_FILE so that underlying filesystem does not end up using overlayfs file object pointer. There are no good use cases yet so for now clear ATTR_FILE. fuse seems to be one user which can use this. But it can work even without this. So it is not mandatory to pass ATTR_FILE to fuse. Signed-off-by:
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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 12 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:
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