linux-kernel - [PATCH] Freeing dst when the reference count <0 causes general protection fault, it could be a major security flaw as rogue app can modify dst to crash kernel.

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Message-Id: <1410596833-2548-1-git-send-email-shakilk1729@gmail.com>
Date:	Sat, 13 Sep 2014 01:27:13 -0700
From:	Shakil A Khan <shakilk1729@...il.com>
To:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	edumazet@...gle.com, davem@...emloft.net,
	Shakil A Khan <shakilk1729@...il.com>
Subject: [PATCH] Freeing dst when the reference count <0 causes general protection fault, it could be a major security flaw as rogue app can modify dst to crash kernel.

Signed-off-by: Shakil A Khan <shakilk1729@...il.com>
---
 net/core/dst.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/net/core/dst.c b/net/core/dst.c
index a028409..6a848b0 100644
--- a/net/core/dst.c
+++ b/net/core/dst.c
@@ -284,7 +284,10 @@ void dst_release(struct dst_entry *dst)
 		int newrefcnt;
 
 		newrefcnt = atomic_dec_return(&dst->__refcnt);
-		WARN_ON(newrefcnt < 0);
+
+		if (WARN(newrefcnt < 0, "dst reference count less than zero"))
+			return;
+
 		if (unlikely(dst->flags & DST_NOCACHE) && !newrefcnt)
 			call_rcu(&dst->rcu_head, dst_destroy_rcu);
 	}
-- 
1.9.3

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