4.14-stable review patch.  If anyone has any objections, please let me know.

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

From: Li Jinyue <lijin...@huawei.com>

commit fbe0e839d1e22d88810f3ee3e2f1479be4c0aa4a upstream.

UBSAN reports signed integer overflow in kernel/futex.c:

 UBSAN: Undefined behaviour in kernel/futex.c:2041:18
 signed integer overflow:
 0 - -2147483648 cannot be represented in type 'int'

Add a sanity check to catch negative values of nr_wake and nr_requeue.

Signed-off-by: Li Jinyue <lijin...@huawei.com>
Signed-off-by: Thomas Gleixner <t...@linutronix.de>
Cc: pet...@infradead.org
Cc: dvh...@infradead.org
Link: 
https://lkml.kernel.org/r/1513242294-31786-1-git-send-email-lijin...@huawei.com
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>

---
 kernel/futex.c |    3 +++
 1 file changed, 3 insertions(+)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1878,6 +1878,9 @@ static int futex_requeue(u32 __user *uad
        struct futex_q *this, *next;
        DEFINE_WAKE_Q(wake_q);
 
+       if (nr_wake < 0 || nr_requeue < 0)
+               return -EINVAL;
+
        /*
         * When PI not supported: return -ENOSYS if requeue_pi is true,
         * consequently the compiler knows requeue_pi is always false past


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