Messages in this thread | | | Date | Sat, 31 Aug 2019 08:20:36 -0400 | From | Sasha Levin <> | Subject | Re: [PATCH 4.14] tcp: fix tcp_rtx_queue_tail in case of empty retransmit queue |
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On Sat, Aug 24, 2019 at 08:03:51AM +0200, Tim Froidcoeur wrote: >Commit 8c3088f895a0 ("tcp: be more careful in tcp_fragment()") >triggers following stack trace: > >[25244.848046] kernel BUG at ./include/linux/skbuff.h:1406! >[25244.859335] RIP: 0010:skb_queue_prev+0x9/0xc >[25244.888167] Call Trace: >[25244.889182] <IRQ> >[25244.890001] tcp_fragment+0x9c/0x2cf >[25244.891295] tcp_write_xmit+0x68f/0x988 >[25244.892732] __tcp_push_pending_frames+0x3b/0xa0 >[25244.894347] tcp_data_snd_check+0x2a/0xc8 >[25244.895775] tcp_rcv_established+0x2a8/0x30d >[25244.897282] tcp_v4_do_rcv+0xb2/0x158 >[25244.898666] tcp_v4_rcv+0x692/0x956 >[25244.899959] ip_local_deliver_finish+0xeb/0x169 >[25244.901547] __netif_receive_skb_core+0x51c/0x582 >[25244.903193] ? inet_gro_receive+0x239/0x247 >[25244.904756] netif_receive_skb_internal+0xab/0xc6 >[25244.906395] napi_gro_receive+0x8a/0xc0 >[25244.907760] receive_buf+0x9a1/0x9cd >[25244.909160] ? load_balance+0x17a/0x7b7 >[25244.910536] ? vring_unmap_one+0x18/0x61 >[25244.911932] ? detach_buf+0x60/0xfa >[25244.913234] virtnet_poll+0x128/0x1e1 >[25244.914607] net_rx_action+0x12a/0x2b1 >[25244.915953] __do_softirq+0x11c/0x26b >[25244.917269] ? handle_irq_event+0x44/0x56 >[25244.918695] irq_exit+0x61/0xa0 >[25244.919947] do_IRQ+0x9d/0xbb >[25244.921065] common_interrupt+0x85/0x85 >[25244.922479] </IRQ> > >tcp_rtx_queue_tail() (called by tcp_fragment()) can call >tcp_write_queue_prev() on the first packet in the queue, which will trigger >the BUG in tcp_write_queue_prev(), because there is no previous packet. > >This happens when the retransmit queue is empty, for example in case of a >zero window. > >Patch is needed for 4.4, 4.9 and 4.14 stable branches.
There needs to be a better explanation of why it's not needed upstream...
-- Thanks, Sasha
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