diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-02-05 15:34:21 +0000 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2018-03-09 16:38:10 +0800 |
| commit | e2846a29d791986520f43612009f0e77380325e4 (patch) | |
| tree | 949493193317c3770ae0ad225768cc0d68d82cd4 | |
| parent | f6111f90227021a261fd22ced479267d96e571e0 (diff) | |
arm64: uaccess: Prevent speculative use of the current addr_limit
commit c2f0ad4fc089 upstream.
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>
Signed-off-by: Alex Shi <alex.shi@linaro.org>
| -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 75363d723262..fc11c50af558 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -62,6 +62,13 @@ extern int fixup_exception(struct pt_regs *regs); 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(); } #define segment_eq(a, b) ((a) == (b)) |