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Commit 5f972797 authored by Greg Kroah-Hartman's avatar Greg Kroah-Hartman
Browse files

Merge tag 'lkdtm-next-part2' of... 

Merge tag 'lkdtm-next-part2' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux into char-misc-next

Kees writes:

- Add new CORRUPT_STACK_STRONG to test -fstack-protector-strong, since
  the existing CORRUPT_STACK test only tested regular -fstack-protector.
- Add pair of tests for checking kernel stack leading/trailing guard pages
  under VMAP_STACK: STACK_GUARD_PAGE_LEADING and STACK_GUARD_PAGE_TRAILING.
parents d9855246 93e78c6b

drivers/misc/lkdtm.h

+3 −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);
@@ -22,6 +23,8 @@ void lkdtm_HUNG_TASK(void); 
void lkdtm_CORRUPT_LIST_ADD(void);

void lkdtm_CORRUPT_LIST_DEL(void);

void lkdtm_CORRUPT_USER_DS(void);

void lkdtm_STACK_GUARD_PAGE_LEADING(void);

void lkdtm_STACK_GUARD_PAGE_TRAILING(void);



/* lkdtm_heap.c */

void lkdtm_OVERWRITE_ALLOCATION(void);

drivers/misc/lkdtm_bugs.c

+48 −3
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/list.h>

#include <linux/sched.h>

#include <linux/sched/signal.h>

#include <linux/sched/task_stack.h>

#include <linux/uaccess.h>



struct lkdtm_list {
@@ -84,16 +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)
@@ -199,6 +215,7 @@ void lkdtm_CORRUPT_LIST_DEL(void) 
		pr_err("list_del() corruption not detected!\n");

}



/* Test if unbalanced set_fs(KERNEL_DS)/set_fs(USER_DS) check exists. */

void lkdtm_CORRUPT_USER_DS(void)

{

	pr_info("setting bad task size limit\n");
@@ -207,3 +224,31 @@ void lkdtm_CORRUPT_USER_DS(void) 
	/* Make sure we do not keep running with a KERNEL_DS! */

	force_sig(SIGKILL, current);

}



/* Test that VMAP_STACK is actually allocating with a leading guard page */

void lkdtm_STACK_GUARD_PAGE_LEADING(void)

{

	const unsigned char *stack = task_stack_page(current);

	const unsigned char *ptr = stack - 1;

	volatile unsigned char byte;



	pr_info("attempting bad read from page below current stack\n");



	byte = *ptr;



	pr_err("FAIL: accessed page before stack!\n");

}



/* Test that VMAP_STACK is actually allocating with a trailing guard page */

void lkdtm_STACK_GUARD_PAGE_TRAILING(void)

{

	const unsigned char *stack = task_stack_page(current);

	const unsigned char *ptr = stack + THREAD_SIZE;

	volatile unsigned char byte;



	pr_info("attempting bad read from page above current stack\n");



	byte = *ptr;



	pr_err("FAIL: accessed page after stack!\n");

}

drivers/misc/lkdtm_core.c

+3 −0
Original line number Diff line number Diff line
@@ -201,6 +201,9 @@ 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),

	CRASHTYPE(OVERWRITE_ALLOCATION),

	CRASHTYPE(WRITE_AFTER_FREE),