From fbe0e839d1e22d88810f3ee3e2f1479be4c0aa4a Mon Sep 17 00:00:00 2001
From: Li Jinyue <lijinyue@huawei.com>
Date: Thu, 14 Dec 2017 17:04:54 +0800
Subject: [PATCH] futex: Prevent overflow by strengthen input validation
Git-commit: fbe0e839d1e22d88810f3ee3e2f1479be4c0aa4a
Patch-mainline: v4.15-rc9
References: CVE-2018-6927,bsc#1080757
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 <lijinyue@huawei.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: peterz@infradead.org
Cc: dvhart@infradead.org
Cc: stable@vger.kernel.org
Link: https://lkml.kernel.org/r/1513242294-31786-1-git-send-email-lijinyue@huawei.com
Acked-by: Takashi Iwai <tiwai@suse.de>
---
kernel/futex.c | 3 +++
1 file changed, 3 insertions(+)
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1874,6 +1874,9 @@ 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;
+
if (requeue_pi) {
/*
* Requeue PI only works on two distinct uaddrs. This