netdev - [patch 2/2 v2] tipc: potential divide by zero in tipc_link_recv

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Message-ID: <20130506193117.GA11399@elgon.mountain>
Date:	Mon, 6 May 2013 22:31:17 +0300
From:	Dan Carpenter <dan.carpenter@...cle.com>
To:	Jon Maloy <jon.maloy@...csson.com>
Cc:	Allan Stephens <allan.stephens@...driver.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	tipc-discussion@...ts.sourceforge.net,
	kernel-janitors@...r.kernel.org,
	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
Subject: [patch 2/2 v2] tipc: potential divide by zero in
 tipc_link_recv_fragment()

The worry here is that fragm_sz could be zero since it comes from
skb->data.

Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
---
v2: fix a whitespace issue

diff --git a/net/tipc/link.c b/net/tipc/link.c
index 3a6064b3..de94493 100644
--- a/net/tipc/link.c
+++ b/net/tipc/link.c
@@ -2524,14 +2524,16 @@ int tipc_link_recv_fragment(struct sk_buff **pending, struct sk_buff **fb,
 		struct tipc_msg *imsg = (struct tipc_msg *)msg_data(fragm);
 		u32 msg_sz = msg_size(imsg);
 		u32 fragm_sz = msg_data_sz(fragm);
-		u32 exp_fragm_cnt = msg_sz/fragm_sz + !!(msg_sz % fragm_sz);
+		u32 exp_fragm_cnt;
 		u32 max =  TIPC_MAX_USER_MSG_SIZE + NAMED_H_SIZE;
+
 		if (msg_type(imsg) == TIPC_MCAST_MSG)
 			max = TIPC_MAX_USER_MSG_SIZE + MCAST_H_SIZE;
-		if (msg_size(imsg) > max) {
+		if (fragm_sz == 0 || msg_size(imsg) > max) {
 			kfree_skb(fbuf);
 			return 0;
 		}
+		exp_fragm_cnt = msg_sz / fragm_sz + !!(msg_sz % fragm_sz);
 		pbuf = tipc_buf_acquire(msg_size(imsg));
 		if (pbuf != NULL) {
 			pbuf->next = *pending;

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