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authorDan Williams <dan.j.williams@intel.com>2018-07-08 13:46:17 -0700
committerIngo Molnar <mingo@kernel.org>2018-07-16 00:05:05 +0200
commit092b31aa2048cf7561a39697974adcd147fbb27b (patch)
tree2bd31cfd50215cff112d65ce0ff7e5b80025f259 /arch/x86/Kconfig
parentca146f6f091e47b3fd18d6a7e76ec0297d202e0f (diff)
download96b-common-092b31aa2048cf7561a39697974adcd147fbb27b.tar.gz
x86/asm/memcpy_mcsafe: Fix copy_to_user_mcsafe() exception handling
All copy_to_user() implementations need to be prepared to handle faults accessing userspace. The __memcpy_mcsafe() implementation handles both mmu-faults on the user destination and machine-check-exceptions on the source buffer. However, the memcpy_mcsafe() wrapper may silently fallback to memcpy() depending on build options and cpu-capabilities. Force copy_to_user_mcsafe() to always use __memcpy_mcsafe() when available, and otherwise disable all of the copy_to_user_mcsafe() infrastructure when __memcpy_mcsafe() is not available, i.e. CONFIG_X86_MCE=n. This fixes crashes of the form: run fstests generic/323 at 2018-07-02 12:46:23 BUG: unable to handle kernel paging request at 00007f0d50001000 RIP: 0010:__memcpy+0x12/0x20 [..] Call Trace: copyout_mcsafe+0x3a/0x50 _copy_to_iter_mcsafe+0xa1/0x4a0 ? dax_alive+0x30/0x50 dax_iomap_actor+0x1f9/0x280 ? dax_iomap_rw+0x100/0x100 iomap_apply+0xba/0x130 ? dax_iomap_rw+0x100/0x100 dax_iomap_rw+0x95/0x100 ? dax_iomap_rw+0x100/0x100 xfs_file_dax_read+0x7b/0x1d0 [xfs] xfs_file_read_iter+0xa7/0xc0 [xfs] aio_read+0x11c/0x1a0 Reported-by: Ross Zwisler <ross.zwisler@linux.intel.com> Tested-by: Ross Zwisler <ross.zwisler@linux.intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Tony Luck <tony.luck@intel.com> Fixes: 8780356ef630 ("x86/asm/memcpy_mcsafe: Define copy_to_iter_mcsafe()") Link: http://lkml.kernel.org/r/153108277790.37979.1486841789275803399.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/Kconfig')
-rw-r--r--arch/x86/Kconfig2
1 files changed, 1 insertions, 1 deletions
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index f1dbb4ee19d7..887d3a7bb646 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -63,7 +63,7 @@ config X86
select ARCH_HAS_PTE_SPECIAL
select ARCH_HAS_REFCOUNT
select ARCH_HAS_UACCESS_FLUSHCACHE if X86_64
- select ARCH_HAS_UACCESS_MCSAFE if X86_64
+ select ARCH_HAS_UACCESS_MCSAFE if X86_64 && X86_MCE
select ARCH_HAS_SET_MEMORY
select ARCH_HAS_SG_CHAIN
select ARCH_HAS_STRICT_KERNEL_RWX