diff options
| author | Mark Rutland <mark.rutland@arm.com> | 2018-04-12 12:11:03 +0100 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-04-20 08:20:43 +0200 |
| commit | 346edd61ce1ce5f2a2a3e81518d86b2b239ed4d4 (patch) | |
| tree | ee4b0c5784b5f97d69b8a2fad1a478d1408f9216 /arch/arm64 | |
| parent | f3ed64a6273ebdc1ddf22262c4e5f724688b7393 (diff) | |
arm64: uaccess: Prevent speculative use of the current addr_limit
From: Will Deacon <will.deacon@arm.com>
commit c2f0ad4fc089cff81cef6a13d04b399980ecbfcc 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: Mark Rutland <mark.rutland@arm.com> [v4.9 backport]
Tested-by: Greg Hackmann <ghackmann@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/arm64')
| -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 a9db051b967f..900397e73fa6 100644 --- a/arch/arm64/include/asm/uaccess.h +++ b/arch/arm64/include/asm/uaccess.h @@ -68,6 +68,13 @@ 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. */ |