| Message ID | 1536576168-40096-7-git-send-email-julien.thierry@arm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | ARM: spectre-v1.1 mitigations | expand |
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 5451e1f..d65ef85 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -69,6 +69,14 @@ static inline void uaccess_restore(unsigned int flags) 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); }
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> --- arch/arm/include/asm/uaccess.h | 8 ++++++++ 1 file changed, 8 insertions(+)