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| author | Julien Thierry <julien.thierry@arm.com> | 2019-02-14 17:49:19 +0300 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2019-02-20 12:18:26 +0300 |
| commit | 0cb3209d8819b58ff85bee7e4cf14a5367c00c1a (patch) | |
| tree | cffd9d4e99850b1d4d46f892af56b531633bf811 | |
| parent | c4fa56d36e8af8376bf6f1829a16a12e3cdfb284 (diff) | |
| download | linux-0cb3209d8819b58ff85bee7e4cf14a5367c00c1a.tar.xz | |
ARM: 8794/1: uaccess: Prevent speculative use of the current addr_limit
Commit 621afc677465db231662ed126ae1f355bf8eac47 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.
Porting commit c2f0ad4fc089cff8 ("arm64: uaccess: Prevent speculative use
of the current addr_limit").
Signed-off-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David A. Long <dave.long@linaro.org>
Reviewed-by: Julien Thierry <julien.thierry@arm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 7b17460127fd..9ae888775743 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -99,6 +99,14 @@ extern int __put_user_bad(void); 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(); + modify_domain(DOMAIN_KERNEL, fs ? DOMAIN_CLIENT : DOMAIN_MANAGER); } |