time: settimeofday: Validate the values of tv from user

commit 6ada1fc0e1c4775de0e043e1bd3ae9d065491aa5 upstream.

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>
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>
[ luis: backported to 3.16: adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>

diff --git a/include/linux/time.h b/include/linux/time.h
index d5d229b2e5af1815d38d7d87d217ee8340b9ec1d..7d532a32ff3abec05d9466ec795f9693c5e49c35 100644 (file)
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -173,6 +173,19 @@ extern void getboottime(struct timespec *ts);
 extern void monotonic_to_bootbased(struct timespec *ts);
 extern void get_monotonic_boottime(struct timespec *ts);
 
+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);
 extern int timekeeping_valid_for_hres(void);
 extern u64 timekeeping_max_deferment(void);

diff --git a/kernel/time.c b/kernel/time.c
index 3c49ab45f822fc2c5e41c6345d36a5d7815ca19c..3eb322e518a31d06eedd0b25e4b5d766c36c0a5e 100644 (file)
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -195,6 +195,10 @@ 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;
        }