linux-stable.git/net/ipv4, branch v5.4.262 Linux kernel stable tree net: annotate data-races around sk->sk_dst_pending_confirm 2023-11-28T16:50:14+00:00 Eric Dumazet edumazet@google.com 2023-09-21T20:28:18+00:00 252bde6b17b8e6e01d3b4798baa17896e76a130d [ Upstream commit eb44ad4e635132754bfbcb18103f1dcb7058aedd ] This field can be read or written without socket lock being held. Add annotations to avoid load-store tearing. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit eb44ad4e635132754bfbcb18103f1dcb7058aedd ]

This field can be read or written without socket lock being held.

Add annotations to avoid load-store tearing.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: fix cookie_init_timestamp() overflows 2023-11-20T09:30:10+00:00 Eric Dumazet edumazet@google.com 2023-10-20T12:57:37+00:00 5105d46146f26f3b67307bea182734f12a63d76d [ Upstream commit 73ed8e03388d16c12fc577e5c700b58a29045a15 ] cookie_init_timestamp() is supposed to return a 64bit timestamp suitable for both TSval determination and setting of skb->tstamp. Unfortunately it uses 32bit fields and overflows after 2^32 * 10^6 nsec (~49 days) of uptime. Generated TSval are still correct, but skb->tstamp might be set far away in the past, potentially confusing other layers. tcp_ns_to_ts() is changed to return a full 64bit value, ts and ts_now variables are changed to u64 type, and TSMASK is removed in favor of shifts operations. While we are at it, change this sequence: ts >>= TSBITS; ts--; ts <<= TSBITS; ts |= options; to: ts -= (1UL << TSBITS); Fixes: 9a568de4818d ("tcp: switch TCP TS option (RFC 7323) to 1ms clock") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 73ed8e03388d16c12fc577e5c700b58a29045a15 ]

cookie_init_timestamp() is supposed to return a 64bit timestamp
suitable for both TSval determination and setting of skb->tstamp.

Unfortunately it uses 32bit fields and overflows after
2^32 * 10^6 nsec (~49 days) of uptime.

Generated TSval are still correct, but skb->tstamp might be set
far away in the past, potentially confusing other layers.

tcp_ns_to_ts() is changed to return a full 64bit value,
ts and ts_now variables are changed to u64 type,
and TSMASK is removed in favor of shifts operations.

While we are at it, change this sequence:
		ts >>= TSBITS;
		ts--;
		ts <<= TSBITS;
		ts |= options;
to:
		ts -= (1UL << TSBITS);

Fixes: 9a568de4818d ("tcp: switch TCP TS option (RFC 7323) to 1ms clock")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: Remove one extra ktime_get_ns() from cookie_init_timestamp 2023-11-20T09:30:09+00:00 Eric Dumazet edumazet@google.com 2019-11-07T19:51:18+00:00 e4e819bdc8f3674cbdc295b670307c0dd981e440 [ Upstream commit 200ecef67b8d09d16ec55f91c92751dcc7a38d40 ] tcp_make_synack() already uses tcp_clock_ns(), and can pass the value to cookie_init_timestamp() to avoid another call to ktime_get_ns() helper. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Stable-dep-of: 73ed8e03388d ("tcp: fix cookie_init_timestamp() overflows") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 200ecef67b8d09d16ec55f91c92751dcc7a38d40 ]

tcp_make_synack() already uses tcp_clock_ns(), and can pass
the value to cookie_init_timestamp() to avoid another call
to ktime_get_ns() helper.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 73ed8e03388d ("tcp: fix cookie_init_timestamp() overflows")
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp_metrics: do not create an entry from tcp_init_metrics() 2023-11-20T09:30:09+00:00 Eric Dumazet edumazet@google.com 2023-09-22T22:03:55+00:00 bed72a332f0286da2d467d2416363cbb07a52889 [ Upstream commit a135798e6e200ecb2f864cecca6d257ba278370c ] tcp_init_metrics() only wants to get metrics if they were previously stored in the cache. Creating an entry is adding useless costs, especially when tcp_no_metrics_save is set. Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit a135798e6e200ecb2f864cecca6d257ba278370c ]

tcp_init_metrics() only wants to get metrics if they were
previously stored in the cache. Creating an entry is adding
useless costs, especially when tcp_no_metrics_save is set.

Fixes: 51c5d0c4b169 ("tcp: Maintain dynamic metrics in local cache.")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp_metrics: properly set tp->snd_ssthresh in tcp_init_metrics() 2023-11-20T09:30:09+00:00 Eric Dumazet edumazet@google.com 2023-09-22T22:03:54+00:00 f3902c0e6f08914a462b13944b6f32baccf769dc [ Upstream commit 081480014a64a69d901f8ef1ffdd56d6085cf87e ] We need to set tp->snd_ssthresh to TCP_INFINITE_SSTHRESH in the case tcp_get_metrics() fails for some reason. Fixes: 9ad7c049f0f7 ("tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 081480014a64a69d901f8ef1ffdd56d6085cf87e ]

We need to set tp->snd_ssthresh to TCP_INFINITE_SSTHRESH
in the case tcp_get_metrics() fails for some reason.

Fixes: 9ad7c049f0f7 ("tcp: RFC2988bis + taking RTT sample from 3WHS for the passive open side")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp_metrics: add missing barriers on delete 2023-11-20T09:30:09+00:00 Eric Dumazet edumazet@google.com 2023-09-22T22:03:53+00:00 b78f2b7774a0e1587764d6554e450b22b3679c96 [ Upstream commit cbc3a153222805d65f821e10f4f78b6afce06f86 ] When removing an item from RCU protected list, we must prevent store-tearing, using rcu_assign_pointer() or WRITE_ONCE(). Fixes: 04f721c671656 ("tcp_metrics: Rewrite tcp_metrics_flush_all") Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: David Ahern <dsahern@kernel.org> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit cbc3a153222805d65f821e10f4f78b6afce06f86 ]

When removing an item from RCU protected list, we must prevent
store-tearing, using rcu_assign_pointer() or WRITE_ONCE().

Fixes: 04f721c671656 ("tcp_metrics: Rewrite tcp_metrics_flush_all")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: David Ahern <dsahern@kernel.org>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: call tcp_try_undo_recovery when an RTOd TFO SYNACK is ACKed 2023-11-20T09:30:09+00:00 Aananth V aananthv@google.com 2023-09-14T14:36:20+00:00 c9b929f7932b043f953430c672d0fcaca23df070 [ Upstream commit e326578a21414738de45f77badd332fb00bd0f58 ] For passive TCP Fast Open sockets that had SYN/ACK timeout and did not send more data in SYN_RECV, upon receiving the final ACK in 3WHS, the congestion state may awkwardly stay in CA_Loss mode unless the CA state was undone due to TCP timestamp checks. However, if tcp_rcv_synrecv_state_fastopen() decides not to undo, then we should enter CA_Open, because at that point we have received an ACK covering the retransmitted SYNACKs. Currently, the icsk_ca_state is only set to CA_Open after we receive an ACK for a data-packet. This is because tcp_ack does not call tcp_fastretrans_alert (and tcp_process_loss) if !prior_packets Note that tcp_process_loss() calls tcp_try_undo_recovery(), so having tcp_rcv_synrecv_state_fastopen() decide that if we're in CA_Loss we should call tcp_try_undo_recovery() is consistent with that, and low risk. Fixes: dad8cea7add9 ("tcp: fix TFO SYNACK undo to avoid double-timestamp-undo") Signed-off-by: Aananth V <aananthv@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit e326578a21414738de45f77badd332fb00bd0f58 ]

For passive TCP Fast Open sockets that had SYN/ACK timeout and did not
send more data in SYN_RECV, upon receiving the final ACK in 3WHS, the
congestion state may awkwardly stay in CA_Loss mode unless the CA state
was undone due to TCP timestamp checks. However, if
tcp_rcv_synrecv_state_fastopen() decides not to undo, then we should
enter CA_Open, because at that point we have received an ACK covering
the retransmitted SYNACKs. Currently, the icsk_ca_state is only set to
CA_Open after we receive an ACK for a data-packet. This is because
tcp_ack does not call tcp_fastretrans_alert (and tcp_process_loss) if
!prior_packets

Note that tcp_process_loss() calls tcp_try_undo_recovery(), so having
tcp_rcv_synrecv_state_fastopen() decide that if we're in CA_Loss we
should call tcp_try_undo_recovery() is consistent with that, and
low risk.

Fixes: dad8cea7add9 ("tcp: fix TFO SYNACK undo to avoid double-timestamp-undo")
Signed-off-by: Aananth V <aananthv@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: fix wrong RTO timeout when received SACK reneging 2023-11-08T10:23:36+00:00 Fred Chen fred.chenchen03@gmail.com 2023-10-21T00:19:47+00:00 54ba3b8267b048c248f7f5df074f4727afa839ac [ Upstream commit d2a0fc372aca561556e765d0a9ec365c7c12f0ad ] This commit fix wrong RTO timeout when received SACK reneging. When an ACK arrived pointing to a SACK reneging, tcp_check_sack_reneging() will rearm the RTO timer for min(1/2*srtt, 10ms) into to the future. But since the commit 62d9f1a6945b ("tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN") merged, the tcp_set_xmit_timer() is moved after tcp_fastretrans_alert()(which do the SACK reneging check), so the RTO timeout will be overwrited by tcp_set_xmit_timer() with icsk_rto instead of 1/2*srtt. Here is a packetdrill script to check this bug: 0 socket(..., SOCK_STREAM, IPPROTO_TCP) = 3 +0 bind(3, ..., ...) = 0 +0 listen(3, 1) = 0 // simulate srtt to 100ms +0 < S 0:0(0) win 32792 <mss 1000, sackOK,nop,nop,nop,wscale 7> +0 > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7> +.1 < . 1:1(0) ack 1 win 1024 +0 accept(3, ..., ...) = 4 +0 write(4, ..., 10000) = 10000 +0 > P. 1:10001(10000) ack 1 // inject sack +.1 < . 1:1(0) ack 1 win 257 <sack 1001:10001,nop,nop> +0 > . 1:1001(1000) ack 1 // inject sack reneging +.1 < . 1:1(0) ack 1001 win 257 <sack 9001:10001,nop,nop> // we expect rto fired in 1/2*srtt (50ms) +.05 > . 1001:2001(1000) ack 1 This fix remove the FLAG_SET_XMIT_TIMER from ack_flag when tcp_check_sack_reneging() set RTO timer with 1/2*srtt to avoid being overwrited later. Fixes: 62d9f1a6945b ("tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN") Signed-off-by: Fred Chen <fred.chenchen03@gmail.com> Reviewed-by: Neal Cardwell <ncardwell@google.com> Tested-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit d2a0fc372aca561556e765d0a9ec365c7c12f0ad ]

This commit fix wrong RTO timeout when received SACK reneging.

When an ACK arrived pointing to a SACK reneging, tcp_check_sack_reneging()
will rearm the RTO timer for min(1/2*srtt, 10ms) into to the future.

But since the commit 62d9f1a6945b ("tcp: fix TLP timer not set when
CA_STATE changes from DISORDER to OPEN") merged, the tcp_set_xmit_timer()
is moved after tcp_fastretrans_alert()(which do the SACK reneging check),
so the RTO timeout will be overwrited by tcp_set_xmit_timer() with
icsk_rto instead of 1/2*srtt.

Here is a packetdrill script to check this bug:
0     socket(..., SOCK_STREAM, IPPROTO_TCP) = 3
+0    bind(3, ..., ...) = 0
+0    listen(3, 1) = 0

// simulate srtt to 100ms
+0    < S 0:0(0) win 32792 <mss 1000, sackOK,nop,nop,nop,wscale 7>
+0    > S. 0:0(0) ack 1 <mss 1460,nop,nop,sackOK,nop,wscale 7>
+.1    < . 1:1(0) ack 1 win 1024

+0    accept(3, ..., ...) = 4

+0    write(4, ..., 10000) = 10000
+0    > P. 1:10001(10000) ack 1

// inject sack
+.1    < . 1:1(0) ack 1 win 257 <sack 1001:10001,nop,nop>
+0    > . 1:1001(1000) ack 1

// inject sack reneging
+.1    < . 1:1(0) ack 1001 win 257 <sack 9001:10001,nop,nop>

// we expect rto fired in 1/2*srtt (50ms)
+.05    > . 1001:2001(1000) ack 1

This fix remove the FLAG_SET_XMIT_TIMER from ack_flag when
tcp_check_sack_reneging() set RTO timer with 1/2*srtt to avoid
being overwrited later.

Fixes: 62d9f1a6945b ("tcp: fix TLP timer not set when CA_STATE changes from DISORDER to OPEN")
Signed-off-by: Fred Chen <fred.chenchen03@gmail.com>
Reviewed-by: Neal Cardwell <ncardwell@google.com>
Tested-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
ipv4: fib: annotate races around nh->nh_saddr_genid and nh->nh_saddr 2023-10-25T09:53:21+00:00 Eric Dumazet edumazet@google.com 2023-10-17T19:23:04+00:00 47419f2aefb3094986545150223063cf28713b8b commit 195374d893681da43a39796e53b30ac4f20400c4 upstream. syzbot reported a data-race while accessing nh->nh_saddr_genid [1] Add annotations, but leave the code lazy as intended. [1] BUG: KCSAN: data-race in fib_select_path / fib_select_path write to 0xffff8881387166f0 of 4 bytes by task 6778 on cpu 1: fib_info_update_nhc_saddr net/ipv4/fib_semantics.c:1334 [inline] fib_result_prefsrc net/ipv4/fib_semantics.c:1354 [inline] fib_select_path+0x292/0x330 net/ipv4/fib_semantics.c:2269 ip_route_output_key_hash_rcu+0x659/0x12c0 net/ipv4/route.c:2810 ip_route_output_key_hash net/ipv4/route.c:2644 [inline] __ip_route_output_key include/net/route.h:134 [inline] ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2872 send4+0x1f5/0x520 drivers/net/wireguard/socket.c:61 wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:2630 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703 worker_thread+0x525/0x730 kernel/workqueue.c:2784 kthread+0x1d7/0x210 kernel/kthread.c:388 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 read to 0xffff8881387166f0 of 4 bytes by task 6759 on cpu 0: fib_result_prefsrc net/ipv4/fib_semantics.c:1350 [inline] fib_select_path+0x1cb/0x330 net/ipv4/fib_semantics.c:2269 ip_route_output_key_hash_rcu+0x659/0x12c0 net/ipv4/route.c:2810 ip_route_output_key_hash net/ipv4/route.c:2644 [inline] __ip_route_output_key include/net/route.h:134 [inline] ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2872 send4+0x1f5/0x520 drivers/net/wireguard/socket.c:61 wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175 wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200 wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline] wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51 process_one_work kernel/workqueue.c:2630 [inline] process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703 worker_thread+0x525/0x730 kernel/workqueue.c:2784 kthread+0x1d7/0x210 kernel/kthread.c:388 ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147 ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304 value changed: 0x959d3217 -> 0x959d3218 Reported by Kernel Concurrency Sanitizer on: CPU: 0 PID: 6759 Comm: kworker/u4:15 Not tainted 6.6.0-rc4-syzkaller-00029-gcbf3a2cb156a #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023 Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker Fixes: 436c3b66ec98 ("ipv4: Invalidate nexthop cache nh_saddr more correctly.") Reported-by: syzbot <syzkaller@googlegroups.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Reviewed-by: Simon Horman <horms@kernel.org> Reviewed-by: David Ahern <dsahern@kernel.org> Link: https://lore.kernel.org/r/20231017192304.82626-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 195374d893681da43a39796e53b30ac4f20400c4 upstream.

syzbot reported a data-race while accessing nh->nh_saddr_genid [1]

Add annotations, but leave the code lazy as intended.

[1]
BUG: KCSAN: data-race in fib_select_path / fib_select_path

write to 0xffff8881387166f0 of 4 bytes by task 6778 on cpu 1:
fib_info_update_nhc_saddr net/ipv4/fib_semantics.c:1334 [inline]
fib_result_prefsrc net/ipv4/fib_semantics.c:1354 [inline]
fib_select_path+0x292/0x330 net/ipv4/fib_semantics.c:2269
ip_route_output_key_hash_rcu+0x659/0x12c0 net/ipv4/route.c:2810
ip_route_output_key_hash net/ipv4/route.c:2644 [inline]
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2872
send4+0x1f5/0x520 drivers/net/wireguard/socket.c:61
wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175
wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

read to 0xffff8881387166f0 of 4 bytes by task 6759 on cpu 0:
fib_result_prefsrc net/ipv4/fib_semantics.c:1350 [inline]
fib_select_path+0x1cb/0x330 net/ipv4/fib_semantics.c:2269
ip_route_output_key_hash_rcu+0x659/0x12c0 net/ipv4/route.c:2810
ip_route_output_key_hash net/ipv4/route.c:2644 [inline]
__ip_route_output_key include/net/route.h:134 [inline]
ip_route_output_flow+0xa6/0x150 net/ipv4/route.c:2872
send4+0x1f5/0x520 drivers/net/wireguard/socket.c:61
wg_socket_send_skb_to_peer+0x94/0x130 drivers/net/wireguard/socket.c:175
wg_socket_send_buffer_to_peer+0xd6/0x100 drivers/net/wireguard/socket.c:200
wg_packet_send_handshake_initiation drivers/net/wireguard/send.c:40 [inline]
wg_packet_handshake_send_worker+0x10c/0x150 drivers/net/wireguard/send.c:51
process_one_work kernel/workqueue.c:2630 [inline]
process_scheduled_works+0x5b8/0xa30 kernel/workqueue.c:2703
worker_thread+0x525/0x730 kernel/workqueue.c:2784
kthread+0x1d7/0x210 kernel/kthread.c:388
ret_from_fork+0x48/0x60 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x11/0x20 arch/x86/entry/entry_64.S:304

value changed: 0x959d3217 -> 0x959d3218

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 6759 Comm: kworker/u4:15 Not tainted 6.6.0-rc4-syzkaller-00029-gcbf3a2cb156a #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
Workqueue: wg-kex-wg1 wg_packet_handshake_send_worker

Fixes: 436c3b66ec98 ("ipv4: Invalidate nexthop cache nh_saddr more correctly.")
Reported-by: syzbot <syzkaller@googlegroups.com>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Simon Horman <horms@kernel.org>
Reviewed-by: David Ahern <dsahern@kernel.org>
Link: https://lore.kernel.org/r/20231017192304.82626-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: tsq: relax tcp_small_queue_check() when rtx queue contains a single skb 2023-10-25T09:53:21+00:00 Eric Dumazet edumazet@google.com 2023-10-17T12:45:26+00:00 8710dbe09e4675592a12a4f2def3a2e399282c47 commit f921a4a5bffa8a0005b190fb9421a7fc1fd716b6 upstream. In commit 75eefc6c59fd ("tcp: tsq: add a shortcut in tcp_small_queue_check()") we allowed to send an skb regardless of TSQ limits being hit if rtx queue was empty or had a single skb, in order to better fill the pipe when/if TX completions were slow. Then later, commit 75c119afe14f ("tcp: implement rb-tree based retransmit queue") accidentally removed the special case for one skb in rtx queue. Stefan Wahren reported a regression in single TCP flow throughput using a 100Mbit fec link, starting from commit 65466904b015 ("tcp: adjust TSO packet sizes based on min_rtt"). This last commit only made the regression more visible, because it locked the TCP flow on a particular behavior where TSQ prevented two skbs being pushed downstream, adding silences on the wire between each TSO packet. Many thanks to Stefan for his invaluable help ! Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue") Link: https://lore.kernel.org/netdev/7f31ddc8-9971-495e-a1f6-819df542e0af@gmx.net/ Reported-by: Stefan Wahren <wahrenst@gmx.net> Tested-by: Stefan Wahren <wahrenst@gmx.net> Signed-off-by: Eric Dumazet <edumazet@google.com> Acked-by: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20231017124526.4060202-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit f921a4a5bffa8a0005b190fb9421a7fc1fd716b6 upstream.

In commit 75eefc6c59fd ("tcp: tsq: add a shortcut in tcp_small_queue_check()")
we allowed to send an skb regardless of TSQ limits being hit if rtx queue
was empty or had a single skb, in order to better fill the pipe
when/if TX completions were slow.

Then later, commit 75c119afe14f ("tcp: implement rb-tree based
retransmit queue") accidentally removed the special case for
one skb in rtx queue.

Stefan Wahren reported a regression in single TCP flow throughput
using a 100Mbit fec link, starting from commit 65466904b015 ("tcp: adjust
TSO packet sizes based on min_rtt"). This last commit only made the
regression more visible, because it locked the TCP flow on a particular
behavior where TSQ prevented two skbs being pushed downstream,
adding silences on the wire between each TSO packet.

Many thanks to Stefan for his invaluable help !

Fixes: 75c119afe14f ("tcp: implement rb-tree based retransmit queue")
Link: https://lore.kernel.org/netdev/7f31ddc8-9971-495e-a1f6-819df542e0af@gmx.net/
Reported-by: Stefan Wahren <wahrenst@gmx.net>
Tested-by: Stefan Wahren <wahrenst@gmx.net>
Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20231017124526.4060202-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>