path: root/tools
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authorPeter Zijlstra <peterz@infradead.org>2019-04-24 09:19:24 +0200
committerIngo Molnar <mingo@kernel.org>2019-04-24 12:19:45 +0200
commit6ae865615fc43d014da2fd1f1bba7e81ee622d1b (patch)
treed13c96f1252d46f49022a1c77d5795f51baf3e87 /tools
parentsched/x86_64: Don't save flags on context switch (diff)
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 'tools')
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