diff options
| author | Will Deacon <will.deacon@arm.com> | 2018-02-05 15:34:21 +0000 |
|---|---|---|
| committer | Alex Shi <alex.shi@linaro.org> | 2018-03-07 13:11:51 +0800 |
| commit | 321ca404e0fc9e34d4e425c93517cbff985c90c3 (patch) | |
| tree | 3aad399e1e479c873ee29673b269765ae004411b | |
| parent | e4faaf1819502d2d040b555bff42929d68afd28f (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>
Conflicts:
no set_thread_flag(TIF_FSCHECK) in arch/arm64/include/asm/uaccess.h
| -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 3531fec798f7..00025c5da432 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -71,6 +71,13 @@ 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(); + + /* * Enable/disable UAO so that copy_to_user() etc can access * kernel memory with the unprivileged instructions. */ |