netdev - [PATCH 3/3] tg3: Fix tx_pending check for MAX_SKB

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: Windows password security audit tool. GUI, reports in PDF.

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

Message-Id: <1408474371-19509-3-git-send-email-bpoirier@suse.de>
Date:	Tue, 19 Aug 2014 11:52:51 -0700
From:	Benjamin Poirier <bpoirier@...e.de>
To:	Prashant Sreedharan <prashant@...adcom.com>,
	Michael Chan <mchan@...adcom.com>
Cc:	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 3/3] tg3: Fix tx_pending check for MAX_SKB_FRAGS

The rest of the driver assumes at least one free descriptor in the tx ring.
Therefore, since an skb with max frags takes up (MAX_SKB_FRAGS + 1)
descriptors, tx_pending must be > (MAX_SKB_FRAGS + 1).

Signed-off-by: Benjamin Poirier <bpoirier@...e.de>
---

Currently, it is possible to set tx_pending = MAX_SKB_FRAGS + 1. This leads to
a netdev watchdog tx timeout. Depending on whether the previous patches in
this series are applied or not, the timeout happens as soon as tx_pending is
updated or after an skb with max frags is submitted for transmission.

I reproduced this bug using the same approach explained in patch 1.
The bug reproduces with tx_pending = 18

---
 drivers/net/ethernet/broadcom/tg3.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/broadcom/tg3.c b/drivers/net/ethernet/broadcom/tg3.c
index 7022f6d..27e2701 100644
--- a/drivers/net/ethernet/broadcom/tg3.c
+++ b/drivers/net/ethernet/broadcom/tg3.c
@@ -12328,7 +12328,7 @@ static int tg3_set_ringparam(struct net_device *dev, struct ethtool_ringparam *e
 	if ((ering->rx_pending > tp->rx_std_ring_mask) ||
 	    (ering->rx_jumbo_pending > tp->rx_jmb_ring_mask) ||
 	    (ering->tx_pending > TG3_TX_RING_SIZE - 1) ||
-	    (ering->tx_pending <= MAX_SKB_FRAGS))
+	    (ering->tx_pending <= MAX_SKB_FRAGS + 1))
 		return -EINVAL;

 	if (netif_running(dev)) {
-- 
1.8.4.5

--
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