Commit-ID: ce788f930b0cdf821de7ee8f84cfe8cf7fcb6311 Gitweb: http://git.kernel.org/tip/ce788f930b0cdf821de7ee8f84cfe8cf7fcb6311 Author: Thomas Gleixner <tglx@xxxxxxxxxxxxx> AuthorDate: Wed, 4 May 2011 08:00:47 +0200 Committer: Thomas Gleixner <tglx@xxxxxxxxxxxxx> CommitDate: Wed, 4 May 2011 08:18:17 +0200 alarmtimer: Check return value of class_find_device() alarmtimer_late_init() uses class_find_device() to find a alarm capable rtc device. The match callback stores a pointer to the name in the char pointer handed in from the call site. alarmtimer_late_init() checks the char pointer for NULL, but the pointer is on the stack and not initialized to NULL before the call. So it can have random content when the match function did not identify a device, which leads to random access in the following rtc_open() call where the pointer is dereferenced Instead of relying on the char pointer, check the return value of class_find_device. If a device is found then the name pointer is valid as well. Reported-by: Ingo Molnar <mingo@xxxxxxx> Cc: John Stultz <john.stultz@xxxxxxxxxx> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> --- kernel/time/alarmtimer.c | 6 ++++-- 1 files changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/time/alarmtimer.c b/kernel/time/alarmtimer.c index 9265014..e5db9b0 100644 --- a/kernel/time/alarmtimer.c +++ b/kernel/time/alarmtimer.c @@ -669,11 +669,13 @@ static int __init has_wakealarm(struct device *dev, void *name_ptr) */ static int __init alarmtimer_init_late(void) { + struct device *dev; char *str; /* Find an rtc device and init the rtc_timer */ - class_find_device(rtc_class, NULL, &str, has_wakealarm); - if (str) + dev = class_find_device(rtc_class, NULL, &str, has_wakealarm); + /* If we have a device then str is valid. See has_wakealarm() */ + if (dev) rtcdev = rtc_class_open(str); if (!rtcdev) { printk(KERN_WARNING "No RTC device found, ALARM timers will" -- To unsubscribe from this list: send the line "unsubscribe linux-tip-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html