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Commit c55d2400 authored by Michael Ellerman's avatar Michael Ellerman Committed by Greg Kroah-Hartman
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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: default avatarMichael Ellerman <mpe@ellerman.id.au>
Acked-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 967b274e

drivers/misc/lkdtm_bugs.c

+2 −1
Original line number Diff line number Diff line
@@ -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)