Daniel Axtens <dja@xxxxxxxxxx> writes: > 3 KASAN self-tests fail on a kernel with both KASAN and FORTIFY_SOURCE: > memchr, memcmp and strlen. I have observed this on x86 and powerpc. > > When FORTIFY_SOURCE is on, a number of functions are replaced with > fortified versions, which attempt to check the sizes of the > operands. However, these functions often directly invoke __builtin_foo() > once they have performed the fortify check. > > This breaks things in 2 ways: > > - the three function calls are technically dead code, and can be > eliminated. When __builtin_ versions are used, the compiler can detect > this. > > - Using __builtins may bypass KASAN checks if the compiler decides to > inline it's own implementation as sequence of instructions, rather than > emit a function call that goes out to a KASAN-instrumented > implementation. > > The patches address each reason in turn. Finally, test_memcmp used a > stack array without explicit initialisation, which can sometimes break > too, so fix that up. Hi all, It doesn't look like this has been picked up yet. Is there anything I can do to help things along? Regards, Daniel > > v2: - some cleanups, don't mess with arch code as I missed some wrinkles. > - add stack array init (patch 3) > > Daniel Axtens (3): > kasan: stop tests being eliminated as dead code with FORTIFY_SOURCE > string.h: fix incompatibility between FORTIFY_SOURCE and KASAN > kasan: initialise array in kasan_memcmp test > > include/linux/string.h | 60 +++++++++++++++++++++++++++++++++--------- > lib/test_kasan.c | 32 +++++++++++++--------- > 2 files changed, 68 insertions(+), 24 deletions(-) > > -- > 2.20.1
