fixes for 4.14

Signed-off-by: Sasha Levin <sashal@kernel.org>

diff --git a/queue-4.14/series b/queue-4.14/series
index 30aa7f515099796819d8f4c565090142027f777d..33dfa88404eb44c090b7ee762ed910450aad1045 100644 (file)
--- a/queue-4.14/series
+++ b/queue-4.14/series
@@ -13,3 +13,4 @@ watchdog-bcm2835_wdt-fix-module-autoload.patch
 drm-bridge-tfp410-fix-memleak-in-get_modes.patch
 scsi-ufs-fix-rx_termination_force_enable-define-valu.patch
 drm-tilcdc-register-cpufreq-notifier-after-we-have-i.patch
+tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch

diff --git a/queue-4.14/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch b/queue-4.14/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch
new file mode 100644 (file)
index 0000000..0462488
--- /dev/null
+++ b/queue-4.14/tcp-fix-tcp_rtx_queue_tail-in-case-of-empty-retransm.patch
@@ -0,0 +1,91 @@
+From dc5084b6b29310bc6279fbfbcbe1431f102568e3 Mon Sep 17 00:00:00 2001
+From: Tim Froidcoeur <tim.froidcoeur@tessares.net>
+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]  <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.
+
+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 <tim.froidcoeur@tessares.net>
+Signed-off-by: Matthieu Baerts <matthieu.baerts@tessares.net>
+Reviewed-by: Christoph Paasch <cpaasch@apple.com>
+Signed-off-by: Sasha Levin <sashal@kernel.org>
+---
+ include/net/tcp.h | 4 ++++
+ 1 file changed, 4 insertions(+)
+
+diff --git a/include/net/tcp.h b/include/net/tcp.h
+index 7994e569644e0..785c4ef4e1bf8 100644
+--- a/include/net/tcp.h
++++ b/include/net/tcp.h
+@@ -1702,6 +1702,10 @@ 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
+