diff options
| author | Michael Ellerman <mpe@ellerman.id.au> | 2016-11-15 18:02:32 +1100 |
|---|---|---|
| committer | Michael Bestas <mkbestas@lineageos.org> | 2020-02-02 01:41:07 +0200 |
| commit | 8c0050c75a7dc7f67d74e70499041cd4b58b0c3c (patch) | |
| tree | aeb18cc738996a1d99447034417b2f5eef4b1640 | |
| parent | 469a6a56f4dd2a16bc3cad3072250e806b705156 (diff) | |
BACKPORT: lkdtm: Prevent the compiler from optimising lkdtm_CORRUPT_STACK()
At least on powerpc with GCC 6, the compiler is smart enough to optimise
lkdtm_CORRUPT_STACK() into an empty function that just returns.
If we print the buffer after we've written to it that prevents the
compiler from optimising away data and the memset().
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Acked-by: Kees Cook <keescook@chromium.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://git.kernel.org/linus/c55d240003ae253d3057dcf93510c9bd64bb7a09
Signed-off-by: Nathan Chancellor <natechancellor@gmail.com>
| -rw-r--r-- | drivers/misc/lkdtm.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index b083bca03abe..ba6b80715c39 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -348,7 +348,8 @@ static noinline void corrupt_stack(void) /* Use default char array length that triggers stack protection. */ char data[8]; - memset((void *)data, 0, 64); + memset((void *)data, 'a', 64); + pr_info("Corrupted stack with '%16s'...\n", data); } static void execute_location(void *dst) |