This is a note to let you know that I've just added the patch titled net/af_iucv: remove WARN_ONCE on malformed RX packets to the 5.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: net-af_iucv-remove-warn_once-on-malformed-rx-packets.patch and it can be found in the queue-5.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. >From 27e9c1de529919d8dd7d072415d3bcae77709300 Mon Sep 17 00:00:00 2001 From: Alexander Egorenkov <egorenar@xxxxxxxxxxxxx> Date: Thu, 28 Jan 2021 12:41:04 +0100 Subject: net/af_iucv: remove WARN_ONCE on malformed RX packets From: Alexander Egorenkov <egorenar@xxxxxxxxxxxxx> commit 27e9c1de529919d8dd7d072415d3bcae77709300 upstream. syzbot reported the following finding: AF_IUCV failed to receive skb, len=0 WARNING: CPU: 0 PID: 522 at net/iucv/af_iucv.c:2039 afiucv_hs_rcv+0x174/0x190 net/iucv/af_iucv.c:2039 CPU: 0 PID: 522 Comm: syz-executor091 Not tainted 5.10.0-rc1-syzkaller-07082-g55027a88ec9f #0 Hardware name: IBM 3906 M04 701 (KVM/Linux) Call Trace: [<00000000b87ea538>] afiucv_hs_rcv+0x178/0x190 net/iucv/af_iucv.c:2039 ([<00000000b87ea534>] afiucv_hs_rcv+0x174/0x190 net/iucv/af_iucv.c:2039) [<00000000b796533e>] __netif_receive_skb_one_core+0x13e/0x188 net/core/dev.c:5315 [<00000000b79653ce>] __netif_receive_skb+0x46/0x1c0 net/core/dev.c:5429 [<00000000b79655fe>] netif_receive_skb_internal+0xb6/0x220 net/core/dev.c:5534 [<00000000b796ac3a>] netif_receive_skb+0x42/0x318 net/core/dev.c:5593 [<00000000b6fd45f4>] tun_rx_batched.isra.0+0x6fc/0x860 drivers/net/tun.c:1485 [<00000000b6fddc4e>] tun_get_user+0x1c26/0x27f0 drivers/net/tun.c:1939 [<00000000b6fe0f00>] tun_chr_write_iter+0x158/0x248 drivers/net/tun.c:1968 [<00000000b4f22bfa>] call_write_iter include/linux/fs.h:1887 [inline] [<00000000b4f22bfa>] new_sync_write+0x442/0x648 fs/read_write.c:518 [<00000000b4f238fe>] vfs_write.part.0+0x36e/0x5d8 fs/read_write.c:605 [<00000000b4f2984e>] vfs_write+0x10e/0x148 fs/read_write.c:615 [<00000000b4f29d0e>] ksys_write+0x166/0x290 fs/read_write.c:658 [<00000000b8dc4ab4>] system_call+0xe0/0x28c arch/s390/kernel/entry.S:415 Last Breaking-Event-Address: [<00000000b8dc64d4>] __s390_indirect_jump_r14+0x0/0xc Malformed RX packets shouldn't generate any warnings because debugging info already flows to dropmon via the kfree_skb(). Signed-off-by: Alexander Egorenkov <egorenar@xxxxxxxxxxxxx> Reviewed-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx> Signed-off-by: Julian Wiedmann <jwi@xxxxxxxxxxxxx> Acked-by: Willem de Bruijn <willemb@xxxxxxxxxx> Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/iucv/af_iucv.c | 1 - 1 file changed, 1 deletion(-) --- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -2176,7 +2176,6 @@ static int afiucv_hs_rcv(struct sk_buff char nullstring[8]; if (!pskb_may_pull(skb, sizeof(*trans_hdr))) { - WARN_ONCE(1, "AF_IUCV failed to receive skb, len=%u", skb->len); kfree_skb(skb); return NET_RX_SUCCESS; } Patches currently in stable-queue which might be from egorenar@xxxxxxxxxxxxx are queue-5.4/net-af_iucv-remove-warn_once-on-malformed-rx-packets.patch