diff options
| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-24 09:19:24 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2019-09-23 21:11:47 +0100 |
| commit | 3d8da4b0b39a343829aa3b6e4887a82f1821de23 (patch) | |
| tree | fc2899462ef69b2b0b13a242ce6ef0b48d66778d /arch/x86/include | |
| parent | c241753cac92a58f69c62110620f773e11c9f64b (diff) | |
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
commit 6ae865615fc43d014da2fd1f1bba7e81ee622d1b upstream.
The __put_user() macro evaluates it's @ptr argument inside the
__uaccess_begin() / __uaccess_end() region. While this would normally
not be expected to be an issue, an UBSAN bug (it ignored -fwrapv,
fixed in GCC 8+) would transform the @ptr evaluation for:
drivers/gpu/drm/i915/i915_gem_execbuffer.c: if (unlikely(__put_user(offset, &urelocs[r-stack].presumed_offset))) {
into a signed-overflow-UB check and trigger the objtool AC validation.
Finish this commit:
2a418cf3f5f1 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation")
and explicitly evaluate all 3 arguments early.
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: luto@kernel.org
Fixes: 2a418cf3f5f1 ("x86/uaccess: Don't leak the AC flag into __put_user() value evaluation")
Link: http://lkml.kernel.org/r/20190424072208.695962771@infradead.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'arch/x86/include')
| -rw-r--r-- | arch/x86/include/asm/uaccess.h | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/x86/include/asm/uaccess.h b/arch/x86/include/asm/uaccess.h index 6778b4e078ce..e99cfcc9af9a 100644 --- a/arch/x86/include/asm/uaccess.h +++ b/arch/x86/include/asm/uaccess.h @@ -422,10 +422,11 @@ do { \ #define __put_user_nocheck(x, ptr, size) \ ({ \ int __pu_err; \ - __typeof__(*(ptr)) __pu_val; \ - __pu_val = x; \ + __typeof__(*(ptr)) __pu_val = (x); \ + __typeof__(ptr) __pu_ptr = (ptr); \ + __typeof__(size) __pu_size = (size); \ __uaccess_begin(); \ - __put_user_size(__pu_val, (ptr), (size), __pu_err, -EFAULT); \ + __put_user_size(__pu_val, __pu_ptr, __pu_size, __pu_err, -EFAULT); \ __uaccess_end(); \ __pu_err; \ }) |