This is a note to let you know that I've just added the patch titled

sch_netem: fix skb leak in netem_enqueue()

to the 4.9-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...

The filename of the patch is: sch_netem-fix-skb-leak-in-netem_enqueue.patch and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.

From foo@baz Wed Mar 28 20:16:33 CEST 2018

From: Alexey Kodanev alexey.kodanev@oracle.com Date: Mon, 5 Mar 2018 20:52:54 +0300 Subject: sch_netem: fix skb leak in netem_enqueue()

From: Alexey Kodanev alexey.kodanev@oracle.com

[ Upstream commit 35d889d10b649fda66121891ec05eca88150059d ]

When we exceed current packets limit and we have more than one segment in the list returned by skb_gso_segment(), netem drops only the first one, skipping the rest, hence kmemleak reports:

unreferenced object 0xffff880b5d23b600 (size 1024): comm "softirq", pid 0, jiffies 4384527763 (age 2770.629s) hex dump (first 32 bytes): 00 80 23 5d 0b 88 ff ff 00 00 00 00 00 00 00 00 ..#]............ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<00000000d8a19b9d>] __alloc_skb+0xc9/0x520 [<000000001709b32f>] skb_segment+0x8c8/0x3710 [<00000000c7b9bb88>] tcp_gso_segment+0x331/0x1830 [<00000000c921cba1>] inet_gso_segment+0x476/0x1370 [<000000008b762dd4>] skb_mac_gso_segment+0x1f9/0x510 [<000000002182660a>] __skb_gso_segment+0x1dd/0x620 [<00000000412651b9>] netem_enqueue+0x1536/0x2590 [sch_netem] [<0000000005d3b2a9>] __dev_queue_xmit+0x1167/0x2120 [<00000000fc5f7327>] ip_finish_output2+0x998/0xf00 [<00000000d309e9d3>] ip_output+0x1aa/0x2c0 [<000000007ecbd3a4>] tcp_transmit_skb+0x18db/0x3670 [<0000000042d2a45f>] tcp_write_xmit+0x4d4/0x58c0 [<0000000056a44199>] tcp_tasklet_func+0x3d9/0x540 [<0000000013d06d02>] tasklet_action+0x1ca/0x250 [<00000000fcde0b8b>] __do_softirq+0x1b4/0x5a3 [<00000000e7ed027c>] irq_exit+0x1e2/0x210

Fix it by adding the rest of the segments, if any, to skb 'to_free' list. Add new __qdisc_drop_all() and qdisc_drop_all() functions because they can be useful in the future if we need to drop segmented GSO packets in other places.

Fixes: 6071bd1aa13e ("netem: Segment GSO packets on enqueue") Signed-off-by: Alexey Kodanev alexey.kodanev@oracle.com Acked-by: Neil Horman nhorman@tuxdriver.com Signed-off-by: David S. Miller davem@davemloft.net Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- include/net/sch_generic.h | 19 +++++++++++++++++++ net/sched/sch_netem.c | 2 +- 2 files changed, 20 insertions(+), 1 deletion(-)

--- a/include/net/sch_generic.h +++ b/include/net/sch_generic.h @@ -675,6 +675,16 @@ static inline void __qdisc_drop(struct s *to_free = skb; }

+static inline void __qdisc_drop_all(struct sk_buff *skb, + struct sk_buff **to_free) +{ + if (skb->prev) + skb->prev->next = *to_free; + else + skb->next = *to_free; + *to_free = skb; +} + static inline unsigned int __qdisc_queue_drop_head(struct Qdisc *sch, struct qdisc_skb_head *qh, struct sk_buff **to_free) @@ -793,6 +803,15 @@ static inline int qdisc_drop(struct sk_b qdisc_qstats_drop(sch);

return NET_XMIT_DROP; +} + +static inline int qdisc_drop_all(struct sk_buff *skb, struct Qdisc *sch, + struct sk_buff **to_free) +{ + __qdisc_drop_all(skb, to_free); + qdisc_qstats_drop(sch); + + return NET_XMIT_DROP; }

/* Length to Time (L2T) lookup in a qdisc_rate_table, to determine how --- a/net/sched/sch_netem.c +++ b/net/sched/sch_netem.c @@ -513,7 +513,7 @@ static int netem_enqueue(struct sk_buff }

if (unlikely(sch->q.qlen >= sch->limit)) - return qdisc_drop(skb, sch, to_free); + return qdisc_drop_all(skb, sch, to_free);

qdisc_qstats_backlog_inc(sch, skb);

Patches currently in stable-queue which might be from alexey.kodanev@oracle.com are

queue-4.9/sch_netem-fix-skb-leak-in-netem_enqueue.patch queue-4.9/dccp-check-sk-for-closed-state-in-dccp_sendmsg.patch