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>
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/include/linux/time.h b/include/linux/time.h
index 8c0216e7d30231e79fc45f0581ebc7f88f6fa3fb..a87b4403600ff6cd540dd1a76f2f7ad9b8e582a5 100644 (file)
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -138,6 +138,19 @@ 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 void read_persistent_clock(struct timespec *ts);
 extern void read_boot_clock(struct timespec *ts);
 extern int update_persistent_clock(struct timespec now);

diff --git a/kernel/time.c b/kernel/time.c
index 060f9611c8be783d5d5c58d2581320aa23204f49..f64e88bd5444fa323417caa8fd1aad4f44b8051b 100644 (file)
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -192,6 +192,10 @@ 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;
        }