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Commit 93e78c6b authored by Kees Cook's avatar Kees Cook
Browse files

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: default avatarKees Cook <keescook@chromium.org>
parent 7b25a85c

drivers/misc/lkdtm.h

+1 −0
Original line number Diff line number Diff line
@@ -14,6 +14,7 @@ void lkdtm_EXCEPTION(void); 
void lkdtm_LOOP(void);

void lkdtm_OVERFLOW(void);

void lkdtm_CORRUPT_STACK(void);

void lkdtm_CORRUPT_STACK_STRONG(void);

void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void);

void lkdtm_SOFTLOCKUP(void);

void lkdtm_HARDLOCKUP(void);

drivers/misc/lkdtm_bugs.c

+18 −3
Original line number Diff line number Diff line
@@ -85,16 +85,31 @@ void lkdtm_OVERFLOW(void) 


static noinline void __lkdtm_CORRUPT_STACK(void *stack)

{

	memset(stack, 'a', 64);

	memset(stack, '\xff', 64);

}



/* This should trip the stack canary, not corrupt the return address. */

noinline void lkdtm_CORRUPT_STACK(void)

{

	/* Use default char array length that triggers stack protection. */

	char data[8];

	char data[8] __aligned(sizeof(void *));



	__lkdtm_CORRUPT_STACK(&data);



	pr_info("Corrupted stack containing char array ...\n");

}



/* Same as above but will only get a canary with -fstack-protector-strong */

noinline void lkdtm_CORRUPT_STACK_STRONG(void)

{

	union {

		unsigned short shorts[4];

		unsigned long *ptr;

	} data __aligned(sizeof(void *));



	__lkdtm_CORRUPT_STACK(&data);



	pr_info("Corrupted stack with '%16s'...\n", data);

	pr_info("Corrupted stack containing union ...\n");

}



void lkdtm_UNALIGNED_LOAD_STORE_WRITE(void)

drivers/misc/lkdtm_core.c

+1 −0
Original line number Diff line number Diff line
@@ -201,6 +201,7 @@ struct crashtype crashtypes[] = { 
	CRASHTYPE(CORRUPT_LIST_DEL),

	CRASHTYPE(CORRUPT_USER_DS),

	CRASHTYPE(CORRUPT_STACK),

	CRASHTYPE(CORRUPT_STACK_STRONG),

	CRASHTYPE(STACK_GUARD_PAGE_LEADING),

	CRASHTYPE(STACK_GUARD_PAGE_TRAILING),

	CRASHTYPE(UNALIGNED_LOAD_STORE_WRITE),