[added,to,the,4.1,stable,tree] futex: Prevent overflow by strengthen input validation

Message ID 20180301152116.1486-181-alexander.levin@microsoft.com
State New
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  • [added,to,the,4.1,stable,tree] futex: Prevent overflow by strengthen input validation
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Commit Message

Sasha Levin March 1, 2018, 3:24 p.m.
From: Li Jinyue <lijinyue@huawei.com>

This patch has been added to the 4.1 stable tree. If you have any
objections, please let us know.




[ Upstream commit fbe0e839d1e22d88810f3ee3e2f1479be4c0aa4a ]

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
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
 kernel/futex.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/kernel/futex.c b/kernel/futex.c
index 959cc4fc6de5..4195616b27d9 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -1514,6 +1514,9 @@  static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
 	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