From 8e71969d45da99b58ced1c656f451305a49939ae Mon Sep 17 00:00:00 2001
From: Paolo Abeni <pabeni@redhat.com>
Date: Wed, 22 Dec 2021 19:39:52 +0100
Subject: [PATCH 26/37] veth: ensure skb entering GRO are not cloned.
Git-commit: 9695b7de5b4760ed22132aca919570c0190cb0ce
Patch-mainline: v5.16-rc7
References: git-fixes
After commit d3256efd8e8b ("veth: allow enabling NAPI even without XDP"),
if GRO is enabled on a veth device and TSO is disabled on the peer
device, TCP skbs will go through the NAPI callback. If there is no XDP
program attached, the veth code does not perform any share check, and
shared/cloned skbs could enter the GRO engine.
Ignat reported a BUG triggered later-on due to the above condition:
[ 53.970529][ C1] kernel BUG at net/core/skbuff.c:3574!
[ 53.981755][ C1] invalid opcode: 0000 [#1] PREEMPT SMP KASAN PTI
[ 53.982634][ C1] CPU: 1 PID: 19 Comm: ksoftirqd/1 Not tainted 5.16.0-rc5+ #25
[ 53.982634][ C1] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 0.0.0 02/06/2015
[ 53.982634][ C1] RIP: 0010:skb_shift+0x13ef/0x23b0
[ 53.982634][ C1] Code: ea 03 0f b6 04 02 48 89 fa 83 e2 07 38 d0
7f 08 84 c0 0f 85 41 0c 00 00 41 80 7f 02 00 4d 8d b5 d0 00 00 00 0f
85 74 f5 ff ff <0f> 0b 4d 8d 77 20 be 04 00 00 00 4c 89 44 24 78 4c 89
f7 4c 89 8c
[ 53.982634][ C1] RSP: 0018:ffff8881008f7008 EFLAGS: 00010246
[ 53.982634][ C1] RAX: 0000000000000000 RBX: ffff8881180b4c80 RCX: 0000000000000000
[ 53.982634][ C1] RDX: 0000000000000002 RSI: ffff8881180b4d3c RDI: ffff88810bc9cac2
[ 53.982634][ C1] RBP: ffff8881008f70b8 R08: ffff8881180b4cf4 R09: ffff8881180b4cf0
[ 53.982634][ C1] R10: ffffed1022999e5c R11: 0000000000000002 R12: 0000000000000590
[ 53.982634][ C1] R13: ffff88810f940c80 R14: ffff88810f940d50 R15: ffff88810bc9cac0
[ 53.982634][ C1] FS: 0000000000000000(0000) GS:ffff888235880000(0000) knlGS:0000000000000000
[ 53.982634][ C1] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 53.982634][ C1] CR2: 00007ff5f9b86680 CR3: 0000000108ce8004 CR4: 0000000000170ee0
[ 53.982634][ C1] Call Trace:
[ 53.982634][ C1] <TASK>
[ 53.982634][ C1] tcp_sacktag_walk+0xaba/0x18e0
[ 53.982634][ C1] tcp_sacktag_write_queue+0xe7b/0x3460
[ 53.982634][ C1] tcp_ack+0x2666/0x54b0
[ 53.982634][ C1] tcp_rcv_established+0x4d9/0x20f0
[ 53.982634][ C1] tcp_v4_do_rcv+0x551/0x810
[ 53.982634][ C1] tcp_v4_rcv+0x22ed/0x2ed0
[ 53.982634][ C1] ip_protocol_deliver_rcu+0x96/0xaf0
[ 53.982634][ C1] ip_local_deliver_finish+0x1e0/0x2f0
[ 53.982634][ C1] ip_sublist_rcv_finish+0x211/0x440
[ 53.982634][ C1] ip_list_rcv_finish.constprop.0+0x424/0x660
[ 53.982634][ C1] ip_list_rcv+0x2c8/0x410
[ 53.982634][ C1] __netif_receive_skb_list_core+0x65c/0x910
[ 53.982634][ C1] netif_receive_skb_list_internal+0x5f9/0xcb0
[ 53.982634][ C1] napi_complete_done+0x188/0x6e0
[ 53.982634][ C1] gro_cell_poll+0x10c/0x1d0
[ 53.982634][ C1] __napi_poll+0xa1/0x530
[ 53.982634][ C1] net_rx_action+0x567/0x1270
[ 53.982634][ C1] __do_softirq+0x28a/0x9ba
[ 53.982634][ C1] run_ksoftirqd+0x32/0x60
[ 53.982634][ C1] smpboot_thread_fn+0x559/0x8c0
[ 53.982634][ C1] kthread+0x3b9/0x490
[ 53.982634][ C1] ret_from_fork+0x22/0x30
[ 53.982634][ C1] </TASK>
Address the issue by skipping the GRO stage for shared or cloned skbs.
To reduce the chance of OoO, try to unclone the skbs before giving up.
v1 -> v2:
- use avoid skb_copy and fallback to netif_receive_skb - Eric
Reported-by: Ignat Korchagin <ignat@cloudflare.com>
Fixes: d3256efd8e8b ("veth: allow enabling NAPI even without XDP")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Tested-by: Ignat Korchagin <ignat@cloudflare.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/b5f61c5602aab01bac8d711d8d1bfab0a4817db7.1640197544.git.pabeni@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Denis Kirjanov <denis.kirjanov@suse.com>
---
drivers/net/veth.c | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index b3f86edf2e90..bd520a9d5409 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -878,8 +878,12 @@ static int veth_xdp_rcv(struct veth_rq *rq, int budget,
stats->xdp_bytes += skb->len;
skb = veth_xdp_rcv_skb(rq, skb, bq, stats);
- if (skb)
- napi_gro_receive(&rq->xdp_napi, skb);
+ if (skb) {
+ if (skb_shared(skb) || skb_unclone(skb, GFP_ATOMIC))
+ netif_receive_skb(skb);
+ else
+ napi_gro_receive(&rq->xdp_napi, skb);
+ }
}
done++;
}
--
2.16.4