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| author | Will Deacon <will.deacon@arm.com> | 2018-02-05 18:34:21 +0300 |
|---|---|---|
| committer | Catalin Marinas <catalin.marinas@arm.com> | 2018-02-07 01:53:37 +0300 |
| commit | c2f0ad4fc089cff81cef6a13d04b399980ecbfcc (patch) | |
| tree | 758d9a7e84a17ed49848d88cc687af1c29624ac7 /arch | |
| parent | 6314d90e64936c584f300a52ef173603fb2461b5 (diff) | |
| download | linux-c2f0ad4fc089cff81cef6a13d04b399980ecbfcc.tar.xz | |
arm64: uaccess: Prevent speculative use of the current addr_limit
A mispredicted conditional call to set_fs could result in the wrong
addr_limit being forwarded under speculation to a subsequent access_ok
check, potentially forming part of a spectre-v1 attack using uaccess
routines.
This patch prevents this forwarding from taking place, but putting heavy
barriers in set_fs after writing the addr_limit.
Reviewed-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/arm64/include/asm/uaccess.h | 7 |
1 files changed, 7 insertions, 0 deletions
diff --git a/arch/arm64/include/asm/uaccess.h b/arch/arm64/include/asm/uaccess.h index e49fe723d72d..2057deed7697 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -42,6 +42,13 @@ static inline void set_fs(mm_segment_t fs) { current_thread_info()->addr_limit = fs; + /* + * Prevent a mispredicted conditional call to set_fs from forwarding + * the wrong address limit to access_ok under speculation. + */ + dsb(nsh); + isb(); + /* On user-mode return, check fs is correct */ set_thread_flag(TIF_FSCHECK); |