diff options
Diffstat (limited to 'drivers/misc/lkdtm.c')
| -rw-r--r-- | drivers/misc/lkdtm.c | 30 |
1 files changed, 20 insertions, 10 deletions
diff --git a/drivers/misc/lkdtm.c b/drivers/misc/lkdtm.c index 9cbd037..4823442 100644 --- a/drivers/misc/lkdtm.c +++ b/drivers/misc/lkdtm.c @@ -49,8 +49,19 @@ #include <linux/ide.h> #endif +/* + * Make sure our attempts to over run the kernel stack doesn't trigger + * a compiler warning when CONFIG_FRAME_WARN is set. Then make sure we + * recurse past the end of THREAD_SIZE by default. + */ +#if defined(CONFIG_FRAME_WARN) && (CONFIG_FRAME_WARN > 0) +#define REC_STACK_SIZE (CONFIG_FRAME_WARN / 2) +#else +#define REC_STACK_SIZE (THREAD_SIZE / 8) +#endif +#define REC_NUM_DEFAULT ((THREAD_SIZE / REC_STACK_SIZE) * 2) + #define DEFAULT_COUNT 10 -#define REC_NUM_DEFAULT 10 #define EXEC_SIZE 64 enum cname { @@ -140,8 +151,7 @@ static DEFINE_SPINLOCK(lock_me_up); static u8 data_area[EXEC_SIZE]; module_param(recur_count, int, 0644); -MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test, "\ - "default is 10"); +MODULE_PARM_DESC(recur_count, " Recursion level for the stack overflow test"); module_param(cpoint_name, charp, 0444); MODULE_PARM_DESC(cpoint_name, " Crash Point, where kernel is to be crashed"); module_param(cpoint_type, charp, 0444); @@ -280,16 +290,16 @@ static int lkdtm_parse_commandline(void) return -EINVAL; } -static int recursive_loop(int a) +static int recursive_loop(int remaining) { - char buf[1024]; + char buf[REC_STACK_SIZE]; - memset(buf,0xFF,1024); - recur_count--; - if (!recur_count) + /* Make sure compiler does not optimize this away. */ + memset(buf, (remaining & 0xff) | 0x1, REC_STACK_SIZE); + if (!remaining) return 0; else - return recursive_loop(a); + return recursive_loop(remaining - 1); } static void do_nothing(void) @@ -333,7 +343,7 @@ static void lkdtm_do_action(enum ctype which) ; break; case CT_OVERFLOW: - (void) recursive_loop(0); + (void) recursive_loop(recur_count); break; case CT_CORRUPT_STACK: corrupt_stack(); |