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Commit 6ada1fc0 authored by Sasha Levin's avatar Sasha Levin Committed by John Stultz
Browse files

time: settimeofday: Validate the values of tv from user 



An unvalidated user input is multiplied by a constant, which can result in
an undefined behaviour for large values. While this is validated later,
we should avoid triggering undefined behaviour.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: stable <stable@vger.kernel.org>
Signed-off-by: default avatarSasha Levin <sasha.levin@oracle.com>
[jstultz: include trivial milisecond->microsecond correction noticed
by Andy]
Signed-off-by: default avatarJohn Stultz <john.stultz@linaro.org>
parent b2776bf7

include/linux/time.h

+13 −0
Original line number Diff line number Diff line
@@ -99,6 +99,19 @@ static inline bool timespec_valid_strict(const struct timespec *ts) 
	return true;

}



static inline bool timeval_valid(const struct timeval *tv)

{

	/* Dates before 1970 are bogus */

	if (tv->tv_sec < 0)

		return false;



	/* Can't have more microseconds then a second */

	if (tv->tv_usec < 0 || tv->tv_usec >= USEC_PER_SEC)

		return false;



	return true;

}



extern struct timespec timespec_trunc(struct timespec t, unsigned gran);



#define CURRENT_TIME		(current_kernel_time())

kernel/time/time.c

+4 −0
Original line number Diff line number Diff line
@@ -196,6 +196,10 @@ SYSCALL_DEFINE2(settimeofday, struct timeval __user *, tv, 
	if (tv) {

		if (copy_from_user(&user_tv, tv, sizeof(*tv)))

			return -EFAULT;



		if (!timeval_valid(&user_tv))

			return -EINVAL;



		new_ts.tv_sec = user_tv.tv_sec;

		new_ts.tv_nsec = user_tv.tv_usec * NSEC_PER_USEC;

	}