- 28 Nov, 2018 31 commits
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Thomas Gleixner authored
Provide the possibility to enable IBPB always in combination with 'prctl' and 'seccomp'. Add the extra command line options and rework the IBPB selection to evaluate the command instead of the mode selected by the STIPB switch case. Signed-off-by:
Thomas Gleixner <tglx@linutronix.de> Reviewed-by:
Ingo Molnar <mingo@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Andy Lutomirski <luto@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Jiri Kosina <jkosina@suse.cz> Cc: Tom Lendacky <thomas.lendacky@amd.com> Cc: Josh Poimboeuf <jpoimboe@redhat.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: David Woodhouse <dwmw@amazon.co.uk> Cc: Tim Chen <tim.c.chen@linux.intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Casey Schaufler <casey.schaufler@intel.com> Cc: Asit Mallick <asit.k.mallick@intel.com> Cc: Arjan van de Ven <arjan@linux.intel.com> Cc: Jon Masters <jcm@redhat.com> Cc: Waiman Long <longman9394@gmail.com> Cc: Greg KH <gregkh@linuxfoundation.org> Cc: Dave Stewart <david.c.stewart@intel.com> Cc: Kees Cook <keescook@chromium.org> Cc: stable@vger.kernel.org Link: https://lkml.kernel.org/r/20181125185006.144047038@linutronix.de
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Thomas Gleixner authored
If 'prctl' mode of user space protection from spectre v2 is selected on the kernel command-line, STIBP and IBPB are applied on tasks which restrict their indirect branch speculation via prctl. SECCOMP enables the SSBD mitigation for sandboxed tasks already, so it makes sense to prevent spectre v2 user space to user space attacks as well. The Intel mitigation guide documents how STIPB works: Setting bit 1 (STIBP) of the IA32_SPEC_CTRL MSR on a logical processor prevents the predicted targets of indirect branches on any logical processor of that core from being controlled by software that executes (or executed previously) on another logical processor of the same core. Ergo setting STIBP protects the task itself from being attacked from a task running on a different hyper-thread and protects the tasks running on different hyper-threads from being attacked. While the document suggests that the branch predictors are shielded between the logical processors, the observed performance regressions suggest that STIBP simply disables the branch predictor more or less completely. Of course the document wording is vague, but the fact that there is also no requirement for issuing IBPB when STIBP is used points clearly in that direction. The kernel still issues IBPB even when STIBP is used until Intel clarifies the whole mechanism. IBPB is issued when the task switches out, so malicious sandbox code cannot mistrain the branch predictor for the next user space task on the same logical processor. Signed-off-by:Jiri Kosina <jkosina@suse.cz> Signed-off-by:
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Thomas Gleixner authored
Now that all prerequisites are in place: - Add the prctl command line option - Default the 'auto' mode to 'prctl' - When SMT state changes, update the static key which controls the conditional STIBP evaluation on context switch. - At init update the static key which controls the conditional IBPB evaluation on context switch. Signed-off-by:
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Thomas Gleixner authored
Add the PR_SPEC_INDIRECT_BRANCH option for the PR_GET_SPECULATION_CTRL and PR_SET_SPECULATION_CTRL prctls to allow fine grained per task control of indirect branch speculation via STIBP and IBPB. Invocations: Check indirect branch speculation status with - prctl(PR_GET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, 0, 0, 0); Enable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_ENABLE, 0, 0); Disable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_DISABLE, 0, 0); Force disable indirect branch speculation with - prctl(PR_SET_SPECULATION_CTRL, PR_SPEC_INDIRECT_BRANCH, PR_SPEC_FORCE_DISABLE, 0, 0); See Documentation/userspace-api/spec_ctrl.rst. Signed-off-by:
Tim Chen <tim.c.chen@linux.intel.com> Signed-off-by:
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Thomas Gleixner authored
The upcoming fine grained per task STIBP control needs to be updated on CPU hotplug as well. Split out the code which controls the strict mode so the prctl control code can be added later. Mark the SMP function call argument __unused while at it. Signed-off-by:
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Thomas Gleixner authored
The seccomp speculation control operates on all tasks of a process, but only the current task of a process can update the MSR immediately. For the other threads the update is deferred to the next context switch. This creates the following situation with Process A and B: Process A task 2 and Process B task 1 are pinned on CPU1. Process A task 2 does not have the speculation control TIF bit set. Process B task 1 has the speculation control TIF bit set. CPU0 CPU1 MSR bit is set ProcB.T1 schedules out ProcA.T2 schedules in MSR bit is cleared ProcA.T1 seccomp_update() set TIF bit on ProcA.T2 ProcB.T1 schedules in MSR is not updated <-- FAIL This happens because the context switch code tries to avoid the MSR update if the speculation control TIF bits of the incoming and the outgoing task are the same. In the worst case ProcB.T1 and ProcA.T2 are the only tasks scheduling back and forth on CPU1, which keeps the MSR stale forever. In theory this could be remedied by IPIs, but chasing the remote task which could be migrated is complex and full of races. The straight forward solution is to avoid the asychronous update of the TIF bit and defer it to the next context switch. The speculation control state is stored in task_struct::atomic_flags by the prctl and seccomp updates already. Add a new TIF_SPEC_FORCE_UPDATE bit and set this after updating the atomic_flags. Check the bit on context switch and force a synchronous update of the speculation control if set. Use the same mechanism for updating the current task. Reported-by:
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Thomas Gleixner authored
The update of the TIF_SSBD flag and the conditional speculation control MSR update is done in the ssb_prctl_set() function directly. The upcoming prctl support for controlling indirect branch speculation via STIBP needs the same mechanism. Split the code out and make it reusable. Reword the comment about updates for other tasks. Signed-off-by:
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Thomas Gleixner authored
The IBPB control code in x86 removed the usage. Remove the functionality which was introduced for this. Signed-off-by:
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Thomas Gleixner authored
The IBPB speculation barrier is issued from switch_mm() when the kernel switches to a user space task with a different mm than the user space task which ran last on the same CPU. An additional optimization is to avoid IBPB when the incoming task can be ptraced by the outgoing task. This optimization only works when switching directly between two user space tasks. When switching from a kernel task to a user space task the optimization fails because the previous task cannot be accessed anymore. So for quite some scenarios the optimization is just adding overhead. The upcoming conditional IBPB support will issue IBPB only for user space tasks which have the TIF_SPEC_IB bit set. This requires to handle the following cases: 1) Switch from a user space task (potential attacker) which has TIF_SPEC_IB set to a user space task (potential victim) which has TIF_SPEC_IB not set. 2) Switch from a user space task (potential attacker) which has TIF_SPEC_IB not set to a user space task (potential victim) which has TIF_SPEC_IB set. This needs to be optimized for the case where the IBPB can be avoided when only kernel threads ran in between user space tasks which belong to the same process. The current check whether two tasks belong to the same context is using the tasks context id. While correct, it's simpler to use the mm pointer because it allows to mangle the TIF_SPEC_IB bit into it. The context id based mechanism requires extra storage, which creates worse code. When a task is scheduled out its TIF_SPEC_IB bit is mangled as bit 0 into the per CPU storage which is used to track the last user space mm which was running on a CPU. This bit can be used together with the TIF_SPEC_IB bit of the incoming task to make the decision whether IBPB needs to be issued or not to cover the two cases above. As conditional IBPB is going to be the default, remove the dubious ptrace check for the IBPB always case and simply issue IBPB always when the process changes. Move the storage to a different place in the struct as the original one created a hole. Signed-off-by: -
Thomas Gleixner authored
The TIF_SPEC_IB bit does not need to be evaluated in the decision to invoke __switch_to_xtra() when: - CONFIG_SMP is disabled - The conditional STIPB mode is disabled The TIF_SPEC_IB bit still controls IBPB in both cases so the TIF work mask checks might invoke __switch_to_xtra() for nothing if TIF_SPEC_IB is the only set bit in the work masks. Optimize it out by masking the bit at compile time for CONFIG_SMP=n and at run time when the static key controlling the conditional STIBP mode is disabled. Signed-off-by:
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Thomas Gleixner authored
Move the conditional invocation of __switch_to_xtra() into an inline function so the logic can be shared between 32 and 64 bit. Remove the handthrough of the TSS pointer and retrieve the pointer directly in the bitmap handling function. Use this_cpu_ptr() instead of the per_cpu() indirection. This is a preparatory change so integration of conditional indirect branch speculation optimization happens only in one place. Signed-off-by:
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Tim Chen authored
To avoid the overhead of STIBP always on, it's necessary to allow per task control of STIBP. Add a new task flag TIF_SPEC_IB and evaluate it during context switch if SMT is active and flag evaluation is enabled by the speculation control code. Add the conditional evaluation to x86_virt_spec_ctrl() as well so the guest/host switch works properly. This has no effect because TIF_SPEC_IB cannot be set yet and the static key which controls evaluation is off. Preparatory patch for adding the control code. [ tglx: Simplify the context switch logic and make the TIF evaluation depend on SMP=y and on the static key controlling the conditional update. Rename it to TIF_SPEC_IB because it controls both STIBP and IBPB ] Signed-off-by:
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Thomas Gleixner authored
Add command line control for user space indirect branch speculation mitigations. The new option is: spectre_v2_user= The initial options are: - on: Unconditionally enabled - off: Unconditionally disabled -auto: Kernel selects mitigation (default off for now) When the spectre_v2= command line argument is either 'on' or 'off' this implies that the application to application control follows that state even if a contradicting spectre_v2_user= argument is supplied. Originally-by: -
Thomas Gleixner authored
There is no point in having two functions and a conditional at the call site. Signed-off-by:
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Thomas Gleixner authored
No point to keep that around. Signed-off-by:
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Thomas Gleixner authored
checkpatch.pl muttered when reshuffling the code: WARNING: static const char * array should probably be static const char * const Fix up all the string arrays. Signed-off-by:
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Thomas Gleixner authored
Reorder the code so it is better grouped. No functional change. Signed-off-by:
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Thomas Gleixner authored
Use the now exposed real SMT state, not the SMT sysfs control knob state. This reflects the state of the system when the mitigation status is queried. This does not change the warning in the VMX launch code. There the dependency on the control knob makes sense because siblings could be brought online anytime after launching the VM. Signed-off-by:
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Thomas Gleixner authored
arch_smt_update() is only called when the sysfs SMT control knob is changed. This means that when SMT is enabled in the sysfs control knob the system is considered to have SMT active even if all siblings are offline. To allow finegrained control of the speculation mitigations, the actual SMT state is more interesting than the fact that siblings could be enabled. Rework the code, so arch_smt_update() is invoked from each individual CPU hotplug function, and simplify the update function while at it. Signed-off-by:
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Thomas Gleixner authored
Make the scheduler's 'sched_smt_present' static key globaly available, so it can be used in the x86 speculation control code. Provide a query function and a stub for the CONFIG_SMP=n case. Signed-off-by:
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Thomas Gleixner authored
CONFIG_SCHED_SMT is enabled by all distros, so there is not a real point to have it configurable. The runtime overhead in the core scheduler code is minimal because the actual SMT scheduling parts are conditional on a static key. This allows to expose the scheduler's SMT state static key to the speculation control code. Alternatively the scheduler's static key could be made always available when CONFIG_SMP is enabled, but that's just adding an unused static key to every other architecture for nothing. Signed-off-by:
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Peter Zijlstra (Intel) authored
Currently the 'sched_smt_present' static key is enabled when at CPU bringup SMT topology is observed, but it is never disabled. However there is demand to also disable the key when the topology changes such that there is no SMT present anymore. Implement this by making the key count the number of cores that have SMT enabled. In particular, the SMT topology bits are set before interrrupts are enabled and similarly, are cleared after interrupts are disabled for the last time and the CPU dies. Signed-off-by:
Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by:
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Tim Chen authored
The logic to detect whether there's a change in the previous and next task's flag relevant to update speculation control MSRs is spread out across multiple functions. Consolidate all checks needed for updating speculation control MSRs into the new __speculation_ctrl_update() helper function. This makes it easy to pick the right speculation control MSR and the bits in MSR_IA32_SPEC_CTRL that need updating based on TIF flags changes. Originally-by:
Thomas Lendacky <Thomas.Lendacky@amd.com> Signed-off-by:
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Thomas Gleixner authored
During context switch, the SSBD bit in SPEC_CTRL MSR is updated according to changes of the TIF_SSBD flag in the current and next running task. Currently, only the bit controlling speculative store bypass disable in SPEC_CTRL MSR is updated and the related update functions all have "speculative_store" or "ssb" in their names. For enhanced mitigation control other bits in SPEC_CTRL MSR need to be updated as well, which makes the SSB names inadequate. Rename the "speculative_store*" functions to a more generic name. No functional change. Signed-off-by:
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Tim Chen authored
If enhanced IBRS is active, STIBP is redundant for mitigating Spectre v2 user space exploits from hyperthread sibling. Disable STIBP when enhanced IBRS is used. Signed-off-by:
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Tim Chen authored
The Spectre V2 printout in cpu_show_common() handles conditionals for the various mitigation methods directly in the sprintf() argument list. That's hard to read and will become unreadable if more complex decisions need to be made for a particular method. Move the conditionals for STIBP and IBPB string selection into helper functions, so they can be extended later on. Signed-off-by:
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Tim Chen authored
Signed-off-by:
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Tim Chen authored
Remove the unnecessary 'else' statement in spectre_v2_parse_cmdline() to save an indentation level. Signed-off-by:
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Tim Chen authored
"Reduced Data Speculation" is an obsolete term. The correct new name is "Speculative store bypass disable" - which is abbreviated into SSBD. Signed-off-by:
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Zhenzhong Duan authored
Now that CONFIG_RETPOLINE hard depends on compiler support, there is no reason to keep the minimal retpoline support around which only provided basic protection in the assembly files. Suggested-by:
Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by:
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Zhenzhong Duan authored
Since retpoline capable compilers are widely available, make CONFIG_RETPOLINE hard depend on the compiler capability. Break the build when CONFIG_RETPOLINE is enabled and the compiler does not support it. Emit an error message in that case: "arch/x86/Makefile:226: *** You are building kernel with non-retpoline compiler, please update your compiler.. Stop." [dwmw: Fail the build with non-retpoline compiler] Suggested-by:
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- 25 Nov, 2018 5 commits
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Linus Torvalds authored
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git://git.infradead.org/users/hch/dma-mappingLinus Torvalds authored
Pull dma-mapping fixes from Christoph Hellwig: "Two dma-direct / swiotlb regressions fixes: - zero is a valid physical address on some arm boards, we can't use it as the error value - don't try to cache flush the error return value (no matter what it is)" * tag 'dma-mapping-4.20-3' of git://git.infradead.org/users/hch/dma-mapping: swiotlb: Skip cache maintenance on map error dma-direct: Make DIRECT_MAPPING_ERROR viable for SWIOTLB -
git://git.linux-nfs.org/projects/trondmy/linux-nfsLinus Torvalds authored
Pull NFS client bugfixes from Trond Myklebust: - Fix a NFSv4 state manager deadlock when returning a delegation - NFSv4.2 copy do not allocate memory under the lock - flexfiles: Use the correct stateid for IO in the tightly coupled case * tag 'nfs-for-4.20-4' of git://git.linux-nfs.org/projects/trondmy/linux-nfs: flexfiles: use per-mirror specified stateid for IO NFSv4.2 copy do not allocate memory under the lock NFSv4: Fix a NFSv4 state manager deadlock
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Luc Van Oostenryck authored
I'm taking over the maintainance of Sparse so add myself as maintainer and move Christopher's info to CREDITS. Signed-off-by:
Luc Van Oostenryck <luc.vanoostenryck@gmail.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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git://git.infradead.org/users/willy/linux-daxLinus Torvalds authored
Pull XArray updates from Matthew Wilcox: "We found some bugs in the DAX conversion to XArray (and one bug which predated the XArray conversion). There were a couple of bugs in some of the higher-level functions, which aren't actually being called in today's kernel, but surfaced as a result of converting existing radix tree & IDR users over to the XArray. Some of the other changes to how the higher-level APIs work were also motivated by converting various users; again, they're not in use in today's kernel, so changing them has a low probability of introducing a bug. Dan can still trigger a bug in the DAX code with hot-offline/online, and we're working on tracking that down" * tag 'xarray-4.20-rc4' of git://git.infradead.org/users/willy/linux-dax: XArray tests: Add missing locking dax: Avoid losing wakeup in dax_lock_mapping_entry dax: Fix huge page faults dax: Fix dax_unlock_mapping_entry for PMD pages dax: Reinstate RCU protection of inode dax: Make sure the unlocking entry isn't locked dax: Remove optimisation from dax_lock_mapping_entry XArray tests: Correct some 64-bit assumptions XArray: Correct xa_store_range XArray: Fix Documentation XArray: Handle NULL pointers differently for allocation XArray: Unify xa_store and __xa_store XArray: Add xa_store_bh() and xa_store_irq() XArray: Turn xa_erase into an exported function XArray: Unify xa_cmpxchg and __xa_cmpxchg XArray: Regularise xa_reserve nilfs2: Use xa_erase_irq XArray: Export __xa_foo to non-GPL modules XArray: Fix xa_for_each with a single element at 0
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- 24 Nov, 2018 4 commits
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git://git.kernel.org/pub/scm/linux/kernel/git/hid/hidLinus Torvalds authored
Pull HID fixes from Jiri Kosina: - revert of the high-resolution scrolling feature, as it breaks certain hardware due to incompatibilities between Logitech and Microsoft worlds. Peter Hutterer is working on a fixed implementation. Until that is finished, revert by Benjamin Tissoires. - revert of incorrect strncpy->strlcpy conversion in uhid, from David Herrmann - fix for buggy sendfile() implementation on uhid device node, from Eric Biggers - a few assorted device-ID specific quirks * 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/hid/hid: Revert "Input: Add the `REL_WHEEL_HI_RES` event code" Revert "HID: input: Create a utility class for counting scroll events" Revert "HID: logitech: Add function to enable HID++ 1.0 "scrolling acceleration"" Revert "HID: logitech: Enable high-resolution scrolling on Logitech mice" Revert "HID: logitech: Use LDJ_DEVICE macro for existing Logitech mice" Revert "HID: logitech: fix a used uninitialized GCC warning" Revert "HID: input: simplify/fix high-res scroll event handling" HID: Add quirk for Primax PIXART OEM mice HID: i2c-hid: Disable runtime PM for LG touchscreen HID: multitouch: Add pointstick support for Cirque Touchpad HID: steam: remove input device when a hid client is running. Revert "HID: uhid: use strlcpy() instead of strncpy()" HID: uhid: forbid UHID_CREATE under KERNEL_DS or elevated privileges HID: input: Ignore battery reported by Symbol DS4308 HID: Add quirk for Microsoft PIXART OEM mouse
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git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linuxLinus Torvalds authored
Pull arm64 fixes from Catalin Marinas:: - Fix wrong conflict resolution around CONFIG_ARM64_SSBD - Fix sparse warning on unsigned long constant * tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux: arm64: cpufeature: Fix mismerge of CONFIG_ARM64_SSBD block arm64: sysreg: fix sparse warnings
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git://git.kernel.org/pub/scm/linux/kernel/git/davem/netLinus Torvalds authored
Pull networking fixes from David Miller: 1) Need to take mutex in ath9k_add_interface(), from Dan Carpenter. 2) Fix mt76 build without CONFIG_LEDS_CLASS, from Arnd Bergmann. 3) Fix socket wmem accounting in SCTP, from Xin Long. 4) Fix failed resume crash in ena driver, from Arthur Kiyanovski. 5) qed driver passes bytes instead of bits into second arg of bitmap_weight(). From Denis Bolotin. 6) Fix reset deadlock in ibmvnic, from Juliet Kim. 7) skb_scrube_packet() needs to scrub the fwd marks too, from Petr Machata. 8) Make sure older TCP stacks see enough dup ACKs, and avoid doing SACK compression during this period, from Eric Dumazet. 9) Add atomicity to SMC protocol cursor handling, from Ursula Braun. 10) Don't leave dangling error pointer if bpf_prog_add() fails in thunderx driver, from Lorenzo Bianconi. Also, when we unmap TSO headers, set sq->tso_hdrs to NULL. 11) Fix race condition over state variables in act_police, from Davide Caratti. 12) Disable guest csum in the presence of XDP in virtio_net, from Jason Wang. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net: (64 commits) net: gemini: Fix copy/paste error net: phy: mscc: fix deadlock in vsc85xx_default_config dt-bindings: dsa: Fix typo in "probed" net: thunderx: set tso_hdrs pointer to NULL in nicvf_free_snd_queue net: amd: add missing of_node_put() team: no need to do team_notify_peers or team_mcast_rejoin when disabling port virtio-net: fail XDP set if guest csum is negotiated virtio-net: disable guest csum during XDP set net/sched: act_police: add missing spinlock initialization net: don't keep lonely packets forever in the gro hash net/ipv6: re-do dad when interface has IFF_NOARP flag change packet: copy user buffers before orphan or clone ibmvnic: Update driver queues after change in ring size support ibmvnic: Fix RX queue buffer cleanup net: thunderx: set xdp_prog to NULL if bpf_prog_add fails net/dim: Update DIM start sample after each DIM iteration net: faraday: ftmac100: remove netif_running(netdev) check before disabling interrupts net/smc: use after free fix in smc_wr_tx_put_slot() net/smc: atomic SMCD cursor handling net/smc: add SMC-D shutdown signal ... -
git://git.kernel.org/pub/scm/fs/xfs/xfs-linuxLinus Torvalds authored
Pull xfs fixes from Darrick Wong: "Dave and I have continued our work fixing corruption problems that can be found when running long-term burn-in exercisers on xfs. Here are some patches fixing most of the problems, but there will likely be more. :/ - Numerous corruption fixes for copy on write - Numerous corruption fixes for blocksize < pagesize writes - Don't miscalculate AG reservations for small final AGs - Fix page cache truncation to work properly for reflink and extent shifting - Fix use-after-free when retrying failed inode/dquot buffer logging - Fix corruptions seen when using copy_file_range in directio mode" * tag 'xfs-4.20-fixes-2' of git://git.kernel.org/pub/scm/fs/xfs/xfs-linux: iomap: readpages doesn't zero page tail beyond EOF vfs: vfs_dedupe_file_range() doesn't return EOPNOTSUPP iomap: dio data corruption and spurious errors when pipes fill iomap: sub-block dio needs to zeroout beyond EOF iomap: FUA is wrong for DIO O_DSYNC writes into unwritten extents xfs: delalloc -> unwritten COW fork allocation can go wrong xfs: flush removing page cache in xfs_reflink_remap_prep xfs: extent shifting doesn't fully invalidate page cache xfs: finobt AG reserves don't consider last AG can be a runt xfs: fix transient reference count error in xfs_buf_resubmit_failed_buffers xfs: uncached buffer tracing needs to print bno xfs: make xfs_file_remap_range() static xfs: fix shared extent data corruption due to missing cow reservation
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