3.16.57-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Alexey Kodanev <alexey.kodanev@xxxxxxxxxx>
commit 35d889d10b649fda66121891ec05eca88150059d upstream.
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@xxxxxxxxxx>
Acked-by: Neil Horman <nhorman@xxxxxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
[bwh: Backported to 3.16:
- The reshape_fail operation still exists, so keep calling it here if the
skb did not require segmentation
- We don't have a to_free list, so free directly in qdisc_drop_all()
- Open-code qdisc_qstats_drop()]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
--- a/include/net/sch_generic.h
+++ b/include/net/sch_generic.h
@@ -656,6 +656,14 @@ static inline int qdisc_drop(struct sk_b
return NET_XMIT_DROP;
}
+static inline int qdisc_drop_all(struct sk_buff *skb, struct Qdisc *sch)
+{
+ kfree_skb_list(skb);
+ sch->qstats.drops++;
+
+ return NET_XMIT_DROP;
+}
+
static inline int qdisc_reshape_fail(struct sk_buff *skb, struct Qdisc *sch)
{
sch->qstats.drops++;
--- a/net/sched/sch_netem.c
+++ b/net/sched/sch_netem.c
@@ -511,8 +511,12 @@ static int netem_enqueue(struct sk_buff
1<<(prandom_u32() % 8);
}
- if (unlikely(skb_queue_len(&sch->q) >= sch->limit))
+ if (unlikely(skb_queue_len(&sch->q) >= sch->limit)) {
+ /* qdisc_reshape_fail() can't handle segmented skb */
+ if (segs)
+ return qdisc_drop_all(skb, sch);
return qdisc_reshape_fail(skb, sch);
+ }
sch->qstats.backlog += qdisc_pkt_len(skb);
