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

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

From: Li Jinyue <[email protected]>

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 <[email protected]>
Signed-off-by: Thomas Gleixner <[email protected]>
Cc: [email protected]
Cc: [email protected]
Link: 
https://lkml.kernel.org/r/[email protected]
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <[email protected]>
---
 kernel/futex.c | 3 +++
 1 file changed, 3 insertions(+)

--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1531,6 +1531,9 @@ static int futex_requeue(u32 __user *uad
        struct futex_hash_bucket *hb1, *hb2;
        struct futex_q *this, *next;
 
+       if (nr_wake < 0 || nr_requeue < 0)
+               return -EINVAL;
+
        if (requeue_pi) {
                /*
                 * Requeue PI only works on two distinct uaddrs. This

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