From: Alexander Egorenkov egorenar@linux.ibm.com
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@linux.ibm.com Reviewed-by: Julian Wiedmann jwi@linux.ibm.com Signed-off-by: Julian Wiedmann jwi@linux.ibm.com Acked-by: Willem de Bruijn willemb@google.com Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/iucv/af_iucv.c | 1 - 1 file changed, 1 deletion(-)
--- a/net/iucv/af_iucv.c +++ b/net/iucv/af_iucv.c @@ -2036,7 +2036,6 @@ 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; }