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: Sasha Levin <sasha.levin@oracle.com>
[jstultz: include trivial milisecond->microsecond correction noticed
by Andy]
Signed-off-by: John Stultz <john.stultz@linaro.org>

diff --git a/include/linux/time.h b/include/linux/time.h
index 8c42cf8d24440a595a670f0ae9db8edb47fcec1c..5989b0ead1ec997fd03696ff410a988ce7b0952e 100644 (file)
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -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())

diff --git a/kernel/time/time.c b/kernel/time/time.c
index a9ae20fb0b11ca879220b7c80467b7485fb3914f..22d5d3b73970d9990eb3f0284b1417116177da1d 100644 (file)
--- a/kernel/time/time.c
+++ b/kernel/time/time.c
@@ -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;
        }