lkdtm: Add -fstack-protector-strong test
There wasn't an LKDTM test to distinguish between -fstack-protector and -fstack-protector-strong in use. This adds CORRUPT_STACK_STRONG to see the difference. Also adjusts the stack-clobber value to 0xff so execution won't potentially jump into userspace when the stack protector is missing. Signed-off-by: Kees Cook <keescook@chromium.org>
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@@ -85,16 +85,31 @@ void lkdtm_OVERFLOW(void)
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static noinline void __lkdtm_CORRUPT_STACK(void *stack)
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{
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memset(stack, 'a', 64);
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memset(stack, '\xff', 64);
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}
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/* This should trip the stack canary, not corrupt the return address. */
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noinline void lkdtm_CORRUPT_STACK(void)
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{
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/* Use default char array length that triggers stack protection. */
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char data[8];
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char data[8] __aligned(sizeof(void *));
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__lkdtm_CORRUPT_STACK(&data);
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pr_info("Corrupted stack with '%16s'...\n", data);
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pr_info("Corrupted stack containing char array ...\n");
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}
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/* Same as above but will only get a canary with -fstack-protector-strong */
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noinline void lkdtm_CORRUPT_STACK_STRONG(void)
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{
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union {
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unsigned short shorts[4];
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unsigned long *ptr;
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} data __aligned(sizeof(void *));
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__lkdtm_CORRUPT_STACK(&data);
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pr_info("Corrupted stack containing union ...\n");
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}
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void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)
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