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Subject[PATCH 3.4 088/176] time: settimeofday: Validate the values of tv from user
Date
From: Sasha Levin <sasha.levin@oracle.com>

3.4.107-rc1 review patch. If anyone has any objections, please let me know.

------------------


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>
[lizf: Backported to 3.4: adjust filename]
Signed-off-by: Zefan Li <lizefan@huawei.com>
---
include/linux/time.h | 13 +++++++++++++
kernel/time.c | 4 ++++
2 files changed, 17 insertions(+)

diff --git a/include/linux/time.h b/include/linux/time.h
index 03dce74..bf1bb61 100644
--- a/include/linux/time.h
+++ b/include/linux/time.h
@@ -189,6 +189,19 @@ 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 a095290..0864d70 100644
--- a/kernel/time.c
+++ b/kernel/time.c
@@ -186,6 +186,10 @@ 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;
}
--
1.9.1


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