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authorMichael Ellerman <mpe@ellerman.id.au>2016-11-15 10:02:32 +0300
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2016-11-15 21:26:06 +0300
commitc55d240003ae253d3057dcf93510c9bd64bb7a09 (patch)
treec80233dfdea2ba01b6a627fbe9cbc52a45df203c /drivers/misc
parent967b274e02e18c9fbb4d19b96a89bd0afbc77b7a (diff)
downloadlinux-c55d240003ae253d3057dcf93510c9bd64bb7a09.tar.xz
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>
Diffstat (limited to 'drivers/misc')
-rw-r--r--drivers/misc/lkdtm_bugs.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/misc/lkdtm_bugs.c b/drivers/misc/lkdtm_bugs.c
index 182ae1894b32..30e62dd7e7ca 100644
--- a/drivers/misc/lkdtm_bugs.c
+++ b/drivers/misc/lkdtm_bugs.c
@@ -80,7 +80,8 @@ noinline void lkdtm_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);
}
void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)