netdev - [PATCH net] net: Prevent infinite while loop in skb_tx

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-next>] [day] [month] [year] [list]

Message-Id: <1635152728-28535-1-git-send-email-michael.chan@broadcom.com>
Date:   Mon, 25 Oct 2021 05:05:28 -0400
From:   Michael Chan <michael.chan@...adcom.com>
To:     davem@...emloft.net
Cc:     netdev@...r.kernel.org, kuba@...nel.org, gospo@...adcom.com
Subject: [PATCH net] net: Prevent infinite while loop in skb_tx_hash()

Drivers call netdev_set_num_tc() and then netdev_set_tc_queue()
to set the queue count and offset for each TC.  So the queue count
and offset for the TCs may be zero for a short period after dev->num_tc
has been set.  If a TX packet is being transmitted at this time in the
code path netdev_pick_tx() -> skb_tx_hash(), skb_tx_hash() may see
nonzero dev->num_tc but zero qcount for the TC.  The while loop that
keeps looping while hash >= qcount will not end.

Fix it by checking the TC's qcount to be nonzero before using it.

Fixes: eadec877ce9c ("net: Add support for subordinate traffic classes to netdev_pick_tx")
Reviewed-by: Andy Gospodarek <gospo@...adcom.com>
Signed-off-by: Michael Chan <michael.chan@...adcom.com>
---
 net/core/dev.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/net/core/dev.c b/net/core/dev.c
index 7ee9fecd3aff..ea2366497697 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3163,6 +3163,12 @@ static u16 skb_tx_hash(const struct net_device *dev,
 
 		qoffset = sb_dev->tc_to_txq[tc].offset;
 		qcount = sb_dev->tc_to_txq[tc].count;
+		if (unlikely(!qcount)) {
+			net_warn_ratelimited("%s: invalid qcount, qoffset %u for tc %u\n",
+					     sb_dev->name, qoffset, tc);
+			qoffset = 0;
+			qcount = dev->real_num_tx_queues;
+		}
 	}
 
 	if (skb_rx_queue_recorded(skb)) {
-- 
2.18.1


Download attachment "smime.p7s" of type "application/pkcs7-signature" (4209 bytes)