After 3cbf4ffba5ee ("net: plumb network namespace into __skb_flow_dissect") we have to provide a net pointer to __skb_flow_dissect(), either via skb->dev, skb->sk, or a user provided pointer. In the following case, syzbot was able to cook a bare skb. WARNING: net/core/flow_dissector.c:1131 at __skb_flow_dissect+0xb57/0x68b0 net/core/flow_dissector.c:1131, CPU#1: syz.2.1418/11053 Call Trace: bond_flow_dissect drivers/net/bonding/bond_main.c:4093 [inline] __bond_xmit_hash+0x2d7/0xba0 drivers/net/bonding/bond_main.c:4157 bond_xmit_hash_xdp drivers/net/bonding/bond_main.c:4208 [inline] bond_xdp_xmit_3ad_xor_slave_get drivers/net/bonding/bond_main.c:5139 [inline] bond_xdp_get_xmit_slave+0x1fd/0x710 drivers/net/bonding/bond_main.c:5515 xdp_master_redirect+0x13f/0x2c0 net/core/filter.c:4388 bpf_prog_run_xdp include/net/xdp.h:700 [inline] bpf_test_run+0x6b2/0x7d0 net/bpf/test_run.c:421 bpf_prog_test_run_xdp+0x795/0x10e0 net/bpf/test_run.c:1390 bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4703 __sys_bpf+0x562/0x860 kernel/bpf/syscall.c:6182 __do_sys_bpf kernel/bpf/syscall.c:6274 [inline] __se_sys_bpf kernel/bpf/syscall.c:6272 [inline] __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6272 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0xec/0xf80 arch/x86/entry/syscall_64.c:94 Fixes: 58deb77cc52d ("bonding: balance ICMP echoes in layer3+4 mode") Reported-by: syzbot+c46409299c70a221415e@syzkaller.appspotmail.com Closes: https://lore.kernel.org/netdev/696faa23.050a0220.4cb9c.001f.GAE@google.com/T/#u Signed-off-by: Eric Dumazet Cc: Matteo Croce Cc: Stanislav Fomichev --- drivers/net/bonding/bond_main.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/drivers/net/bonding/bond_main.c b/drivers/net/bonding/bond_main.c index 0aca6c937297def91d5740dfd456800432b5e343..e7caf400a59cbd9680adea3d1b8ab7a22c78f7e6 100644 --- a/drivers/net/bonding/bond_main.c +++ b/drivers/net/bonding/bond_main.c @@ -4096,8 +4096,9 @@ static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb, const v case BOND_XMIT_POLICY_ENCAP23: case BOND_XMIT_POLICY_ENCAP34: memset(fk, 0, sizeof(*fk)); - return __skb_flow_dissect(NULL, skb, &flow_keys_bonding, - fk, data, l2_proto, nhoff, hlen, 0); + return __skb_flow_dissect(dev_net(bond->dev), skb, + &flow_keys_bonding, fk, data, + l2_proto, nhoff, hlen, 0); default: break; } -- 2.52.0.457.g6b5491de43-goog