netdev - [PATCH] af_packet: check loop for greater than zero in tpacket_fill

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite for Android: free password hash cracker in your pocket

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <4FD4F494.6020102@iogearbox.net>
Date:	Sun, 10 Jun 2012 21:25:08 +0200
From:	Daniel Borkmann <danborkmann@...earbox.net>
To:	"David S. Miller" <davem@...emloft.net>
CC:	"netdev@...r.kernel.org" <netdev@...r.kernel.org>
Subject: [PATCH] af_packet: check loop for greater than zero in tpacket_fill_skb

It could be more safe to check the 'to_write' for 'greater than zero'
instead for 'not zero'. 'to_write' is of type int and subtraction operations
are performed on it, so in the case of malformed values that are
subtracted from 'to_write', it could become less than zero, which is then
interpreted as 'not zero' in the while condition, thus the loop won't
return as expected.

Signed-off-by: Daniel Borkmann <daniel.borkmann@....ee.ethz.ch>
---
 net/packet/af_packet.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c
index 0f66174..3e53680 100644
--- a/net/packet/af_packet.c
+++ b/net/packet/af_packet.c
@@ -2027,7 +2027,7 @@ static int tpacket_fill_skb(struct packet_sock *po, struct sk_buff *skb,
 	skb->truesize += to_write;
 	atomic_add(to_write, &po->sk.sk_wmem_alloc);

-	while (likely(to_write)) {
+	while (likely(to_write > 0)) {
 		nr_frags = skb_shinfo(skb)->nr_frags;

 		if (unlikely(nr_frags >= MAX_SKB_FRAGS)) {
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html