On 11/18/24 10:14, Menglong Dong wrote: > The errno should be replaced with drop reasons in fib_validate_source(), > and the "-EINVAL" shouldn't be returned. And this causes a warning, which > is reported by syzkaller: > > netlink: 'syz-executor371': attribute type 4 has an invalid length. > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 5842 at net/core/skbuff.c:1219 __sk_skb_reason_drop net/core/skbuff.c:1216 [inline] > WARNING: CPU: 0 PID: 5842 at net/core/skbuff.c:1219 sk_skb_reason_drop+0x87/0x380 net/core/skbuff.c:1241 > Modules linked in: > CPU: 0 UID: 0 PID: 5842 Comm: syz-executor371 Not tainted 6.12.0-rc6-syzkaller-01362-ga58f00ed24b8 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/30/2024 > RIP: 0010:__sk_skb_reason_drop net/core/skbuff.c:1216 [inline] > RIP: 0010:sk_skb_reason_drop+0x87/0x380 net/core/skbuff.c:1241 > Code: 00 00 00 fc ff df 41 8d 9e 00 00 fc ff bf 01 00 fc ff 89 de e8 ea 9f 08 f8 81 fb 00 00 fc ff 77 3a 4c 89 e5 e8 9a 9b 08 f8 90 <0f> 0b 90 eb 5e bf 01 00 00 00 89 ee e8 c8 9f 08 f8 85 ed 0f 8e 49 > RSP: 0018:ffffc90003d57078 EFLAGS: 00010293 > RAX: ffffffff898c3ec6 RBX: 00000000fffbffea RCX: ffff8880347a5a00 > RDX: 0000000000000000 RSI: 00000000fffbffea RDI: 00000000fffc0001 > RBP: dffffc0000000000 R08: ffffffff898c3eb6 R09: 1ffff110023eb7d4 > R10: dffffc0000000000 R11: ffffed10023eb7d5 R12: dffffc0000000000 > R13: ffff888011f5bdc0 R14: 00000000ffffffea R15: 0000000000000000 > FS: 000055557d41e380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 000056519d31d608 CR3: 000000007854e000 CR4: 00000000003526f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > kfree_skb_reason include/linux/skbuff.h:1263 [inline] > ip_rcv_finish_core+0xfde/0x1b50 net/ipv4/ip_input.c:424 > ip_list_rcv_finish net/ipv4/ip_input.c:610 [inline] > ip_sublist_rcv+0x3b1/0xab0 net/ipv4/ip_input.c:636 > ip_list_rcv+0x42b/0x480 net/ipv4/ip_input.c:670 > __netif_receive_skb_list_ptype net/core/dev.c:5715 [inline] > __netif_receive_skb_list_core+0x94e/0x980 net/core/dev.c:5762 > __netif_receive_skb_list net/core/dev.c:5814 [inline] > netif_receive_skb_list_internal+0xa51/0xe30 net/core/dev.c:5905 > netif_receive_skb_list+0x55/0x4b0 net/core/dev.c:5957 > xdp_recv_frames net/bpf/test_run.c:280 [inline] > xdp_test_run_batch net/bpf/test_run.c:361 [inline] > bpf_test_run_xdp_live+0x1b5e/0x21b0 net/bpf/test_run.c:390 > bpf_prog_test_run_xdp+0x805/0x11e0 net/bpf/test_run.c:1318 > bpf_prog_test_run+0x2e4/0x360 kernel/bpf/syscall.c:4266 > __sys_bpf+0x48d/0x810 kernel/bpf/syscall.c:5671 > __do_sys_bpf kernel/bpf/syscall.c:5760 [inline] > __se_sys_bpf kernel/bpf/syscall.c:5758 [inline] > __x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:5758 > do_syscall_x64 arch/x86/entry/common.c:52 [inline] > do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83 > entry_SYSCALL_64_after_hwframe+0x77/0x7f > RIP: 0033:0x7f18af25a8e9 > Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48 > RSP: 002b:00007ffee4090af8 EFLAGS: 00000246 ORIG_RAX: 0000000000000141 > RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f18af25a8e9 > RDX: 0000000000000048 RSI: 0000000020000600 RDI: 000000000000000a > RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 > R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 > > Fix it by returning "-SKB_DROP_REASON_IP_LOCAL_SOURCE" instead of > "-EINVAL" in fib_validate_source(). > > Reported-by: syzbot+52fbd90f020788ec7709@xxxxxxxxxxxxxxxxxxxxxxxxx > Closes: https://lore.kernel.org/netdev/6738e539.050a0220.e1c64.0002.GAE@xxxxxxxxxx/ > Fixes: 82d9983ebeb8 ("net: ip: make ip_route_input_noref() return drop reasons") > Signed-off-by: Menglong Dong <dongml2@xxxxxxxxxxxxxxx> Thanks for the quick turnaround! Acked-by: Paolo Abeni <pabeni@xxxxxxxxxx>
