From: Sasha Levin Date: Sun, 1 Sep 2019 00:30:53 +0000 (-0400) Subject: fixes for 4.9 X-Git-Tag: v4.4.191~56 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=002797cf680fed5d1705dfa3ea90e55a885e7fab;p=thirdparty%2Fkernel%2Fstable-queue.git fixes for 4.9 Signed-off-by: Sasha Levin --- diff --git a/queue-4.9/series b/queue-4.9/series index 0b6bd10325a..9d299a091f9 100644 --- a/queue-4.9/series +++ b/queue-4.9/series @@ -52,3 +52,4 @@ usb-host-fotg2-restart-hcd-after-port-reset.patch tools-hv-fix-kvp-and-vss-daemons-exit-code.patch watchdog-bcm2835_wdt-fix-module-autoload.patch scsi-ufs-fix-rx_termination_force_enable-define-valu.patch +tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch diff --git a/queue-4.9/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch b/queue-4.9/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch new file mode 100644 index 00000000000..58dbb2bee87 --- /dev/null +++ b/queue-4.9/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch @@ -0,0 +1,91 @@ +From 2dd0d064cbe48ce6e3d46bf3a57bc55e822e089b Mon Sep 17 00:00:00 2001 +From: Tim Froidcoeur +Date: Sat, 24 Aug 2019 08:03:51 +0200 +Subject: tcp: fix tcp_rtx_queue_tail in case of empty retransmit queue +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +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] +[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] + +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. + +Commit 8c3088f895a0 ("tcp: be more careful in tcp_fragment()") was not a +simple cherry-pick of the original one from master (b617158dc096) +because there is a specific TCP rtx queue only since v4.15. For more +details, please see the commit message of b617158dc096 ("tcp: be more +careful in tcp_fragment()"). + +The BUG() is hit due to the specific code added to versions older than +v4.15. The comment in skb_queue_prev() (include/linux/skbuff.h:1406), +just before the BUG_ON() somehow suggests to add a check before using +it, what Tim did. + +In master, this code path causing the issue will not be taken because +the implementation of tcp_rtx_queue_tail() is different: + + tcp_fragment() → tcp_rtx_queue_tail() → tcp_write_queue_prev() → +skb_queue_prev() → BUG_ON() + +Fixes: 8c3088f895a0 ("tcp: be more careful in tcp_fragment()") +Signed-off-by: Tim Froidcoeur +Signed-off-by: Matthieu Baerts +Reviewed-by: Christoph Paasch +Signed-off-by: Sasha Levin +--- + include/net/tcp.h | 4 ++++ + 1 file changed, 4 insertions(+) + +diff --git a/include/net/tcp.h b/include/net/tcp.h +index a474213ca015b..23814d997e867 100644 +--- a/include/net/tcp.h ++++ b/include/net/tcp.h +@@ -1609,6 +1609,10 @@ static inline struct sk_buff *tcp_rtx_queue_tail(const struct sock *sk) + { + struct sk_buff *skb = tcp_send_head(sk); + ++ /* empty retransmit queue, for example due to zero window */ ++ if (skb == tcp_write_queue_head(sk)) ++ return NULL; ++ + return skb ? tcp_write_queue_prev(sk, skb) : tcp_write_queue_tail(sk); + } + +-- +2.20.1 +