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| author | Peter Zijlstra <peterz@infradead.org> | 2019-04-24 09:19:24 +0200 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2019-04-24 12:19:45 +0200 |
| commit | 6ae865615fc43d014da2fd1f1bba7e81ee622d1b (patch) | |
| tree | d13c96f1252d46f49022a1c77d5795f51baf3e87 /lib/strnlen_user.c | |
| parent | 64604d54d3115fee89598bfb6d8d2252f8a2d114 (diff) | |
| download | linux-6ae865615fc43d014da2fd1f1bba7e81ee622d1b.tar.bz2 | |
x86/uaccess: Dont leak the AC flag into __put_user() argument evaluation
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>
Diffstat (limited to 'lib/strnlen_user.c')
0 files changed, 0 insertions, 0 deletions