diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2018-10-04 00:56:05 -0400 |
|---|---|---|
| committer | David A. Long <dave.long@linaro.org> | 2018-10-30 23:23:46 -0400 |
| commit | 518029530e79cc29a8b32d24903a0be22257e9fc (patch) | |
| tree | 46beaaed9259259d162d750246beccb6bda5989b /arch/arm/include | |
| parent | 142fee8a5498ccd0a377d20c5072b7dc9a2c359b (diff) | |
ARM: spectre-v1: use get_user() for __get_user()
Commit b1cd0a14806321721aae45f5446ed83a3647c914 upstream.
Fixing __get_user() for spectre variant 1 is not sane: we would have to
add address space bounds checking in order to validate that the location
should be accessed, and then zero the address if found to be invalid.
Since __get_user() is supposed to avoid the bounds check, and this is
exactly what get_user() does, there's no point having two different
implementations that are doing the same thing. So, when the Spectre
workarounds are required, make __get_user() an alias of get_user().
Acked-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Signed-off-by: David A. Long <dave.long@linaro.org>
Diffstat (limited to 'arch/arm/include')
| -rw-r--r-- | arch/arm/include/asm/uaccess.h | 16 |
1 files changed, 10 insertions, 6 deletions
diff --git a/arch/arm/include/asm/uaccess.h b/arch/arm/include/asm/uaccess.h index 968b50063431..ecd159b45f12 100644 --- a/arch/arm/include/asm/uaccess.h +++ b/arch/arm/include/asm/uaccess.h @@ -314,6 +314,15 @@ static inline void set_fs(mm_segment_t fs) #define user_addr_max() \ (segment_eq(get_fs(), KERNEL_DS) ? ~0UL : get_fs()) +#ifdef CONFIG_CPU_SPECTRE +/* + * When mitigating Spectre variant 1, it is not worth fixing the non- + * verifying accessors, because we need to add verification of the + * address space there. Force these to use the standard get_user() + * version instead. + */ +#define __get_user(x, ptr) get_user(x, ptr) +#else /* * The "__xxx" versions of the user access functions do not verify the * address space - it must have been done previously with a separate @@ -330,12 +339,6 @@ static inline void set_fs(mm_segment_t fs) __gu_err; \ }) -#define __get_user_error(x, ptr, err) \ -({ \ - __get_user_err((x), (ptr), err); \ - (void) 0; \ -}) - #define __get_user_err(x, ptr, err) \ do { \ unsigned long __gu_addr = (unsigned long)(ptr); \ @@ -395,6 +398,7 @@ do { \ #define __get_user_asm_word(x, addr, err) \ __get_user_asm(x, addr, err, ldr) +#endif #define __put_user(x, ptr) \ ({ \ |