From: "Liu, Changcheng" <changcheng.liu@intel.com>
To: davem@davemloft.net, kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org
Cc: netdev@vger.kernel.org, akpm@linux-foundation.org
Subject: [PATCH] net: deal wrong skb and failure ret from __tcp_retransmit_skb
Date: Thu, 19 Apr 2018 19:26:53 +0800 [thread overview]
Message-ID: <20180419112653.GA108857@sofia> (raw)
Hit below panic due to skb is NULL, WARN wrong skb first.
if __tcp_retransmit_skb return failure e.g. -EAGAIN, it
needn't do further action in tcp_retransmit_skb.
gdb vmlinux
Reading symbols from vmlinux...done.
(gdb) p &((struct tcp_skb_cb *) \
&(((struct sk_buff *)0)->cb[0]))->tcp_gso_segs
$1 = (u16 *) 0x30 <irq_stack_union+48>
[ 9040.917533] BUG: unable to handle kernel NULL pointer dereference at 0000000000000030
[ 9040.926279] IP: tcp_retransmit_skb+0x5c/0xc0
[ 9040.931043] PGD 0 P4D 0
[ 9040.933865] Oops: 0000 [#1] PREEMPT SMP PTI
[ 9040.972151] RIP: 0010:tcp_retransmit_skb+0x5c/0xc0
[ 9040.977496] RSP: 0018:ffff8802bec83e40 EFLAGS: 00010202
[ 9041.062527] Call Trace:
[ 9041.065250] <IRQ>
[ 9041.067489] tcp_retransmit_timer+0x481/0x820
[ 9041.077697] tcp_write_timer_handler+0xe9/0x230
[ 9041.082751] tcp_write_timer+0x75/0x80
[ 9041.086932] call_timer_fn+0x29/0x150
[ 9041.091018] run_timer_softirq+0x411/0x460
[ 9041.105017] __do_softirq+0x115/0x311
[ 9041.109103] irq_exit+0xb0/0xc0
[ 9041.112605] smp_apic_timer_interrupt+0x67/0x140
Signed-off-by: Liu Changcheng <changcheng.liu@intel.com>
diff --git a/net/ipv4/tcp_output.c b/net/ipv4/tcp_output.c
index 383cac0..545b9b3 100644
--- a/net/ipv4/tcp_output.c
+++ b/net/ipv4/tcp_output.c
@@ -2920,7 +2920,10 @@ int __tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
{
struct tcp_sock *tp = tcp_sk(sk);
- int err = __tcp_retransmit_skb(sk, skb, segs);
+ int err = 0;
+
+ WARN_ONCE(!skb, "sk_buff is NULL\n");
+ err = __tcp_retransmit_skb(sk, skb, segs);
if (err == 0) {
#if FASTRETRANS_DEBUG > 0
@@ -2935,6 +2938,8 @@ int tcp_retransmit_skb(struct sock *sk, struct sk_buff *skb, int segs)
if (!tp->retrans_stamp)
tp->retrans_stamp = tcp_skb_timestamp(skb);
+ } else {
+ return err;
}
if (tp->undo_retrans < 0)
--
2.7.4
next reply other threads:[~2018-04-19 11:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-19 11:26 Liu, Changcheng [this message]
2018-04-19 13:40 ` [PATCH] net: deal wrong skb and failure ret from __tcp_retransmit_skb Eric Dumazet
2018-04-19 14:38 ` Liu, Changcheng
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