On Fri, Mar 24, 2023 at 9:31 AM Stefano Garzarella <sgarzare@xxxxxxxxxx> wrote: > > Hi Bobby, > can you take a look at this report? > > It seems related to the changes we made to support skbuff. Could it be a problem of concurrent access to pkt_queue ? IIUC we should hold pkt_queue.lock when we call skb_queue_splice_init() and remove pkt_list_lock. (or hold pkt_list_lock when calling virtio_transport_purge_skbs, but pkt_list_lock seems useless now that we use skbuff) #syz test https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git fff5a5e7f528 --- a/net/vmw_vsock/vsock_loopback.c +++ b/net/vmw_vsock/vsock_loopback.c @@ -15,7 +15,6 @@ struct vsock_loopback { struct workqueue_struct *workqueue; - spinlock_t pkt_list_lock; /* protects pkt_list */ struct sk_buff_head pkt_queue; struct work_struct pkt_work; }; @@ -32,9 +31,7 @@ static int vsock_loopback_send_pkt(struct sk_buff *skb) struct vsock_loopback *vsock = &the_vsock_loopback; int len = skb->len; - spin_lock_bh(&vsock->pkt_list_lock); skb_queue_tail(&vsock->pkt_queue, skb); - spin_unlock_bh(&vsock->pkt_list_lock); queue_work(vsock->workqueue, &vsock->pkt_work); @@ -113,9 +110,9 @@ static void vsock_loopback_work(struct work_struct *work) skb_queue_head_init(&pkts); - spin_lock_bh(&vsock->pkt_list_lock); + spin_lock_bh(&vsock->pkt_queue.lock); skb_queue_splice_init(&vsock->pkt_queue, &pkts); - spin_unlock_bh(&vsock->pkt_list_lock); + spin_unlock_bh(&vsock->pkt_queue.lock); while ((skb = __skb_dequeue(&pkts))) { virtio_transport_deliver_tap_pkt(skb); @@ -132,7 +129,6 @@ static int __init vsock_loopback_init(void) if (!vsock->workqueue) return -ENOMEM; - spin_lock_init(&vsock->pkt_list_lock); skb_queue_head_init(&vsock->pkt_queue); INIT_WORK(&vsock->pkt_work, vsock_loopback_work); > > Thanks, > Stefano > > On Fri, Mar 24, 2023 at 1:52 AM syzbot > <syzbot+befff0a9536049e7902e@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote: > > > > Hello, > > > > syzbot found the following issue on: > > > > HEAD commit: fff5a5e7f528 Merge tag 'for-linus' of git://git.armlinux.o.. > > git tree: upstream > > console+strace: https://syzkaller.appspot.com/x/log.txt?x=1136e97ac80000 > > kernel config: https://syzkaller.appspot.com/x/.config?x=aaa4b45720ca0519 > > dashboard link: https://syzkaller.appspot.com/bug?extid=befff0a9536049e7902e > > compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2 > > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14365781c80000 > > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12eebc66c80000 > > > > Downloadable assets: > > disk image: https://storage.googleapis.com/syzbot-assets/997791f5f9e1/disk-fff5a5e7.raw.xz > > vmlinux: https://storage.googleapis.com/syzbot-assets/0b0155b5eac1/vmlinux-fff5a5e7.xz > > kernel image: https://storage.googleapis.com/syzbot-assets/8d98dd2ba6b6/bzImage-fff5a5e7.xz > > > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > > Reported-by: syzbot+befff0a9536049e7902e@xxxxxxxxxxxxxxxxxxxxxxxxx > > > > general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN > > KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007] > > CPU: 0 PID: 8759 Comm: syz-executor379 Not tainted 6.3.0-rc3-syzkaller-00026-gfff5a5e7f528 #0 > > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 > > RIP: 0010:virtio_transport_purge_skbs+0x139/0x4c0 net/vmw_vsock/virtio_transport_common.c:1370 > > Code: 00 00 00 00 fc ff df 48 89 c2 48 89 44 24 28 48 c1 ea 03 48 8d 04 1a 48 89 44 24 10 eb 29 e8 ee 27 a3 f7 48 89 e8 48 c1 e8 03 <80> 3c 18 00 0f 85 a6 02 00 00 49 39 ec 48 8b 55 00 49 89 ef 0f 84 > > RSP: 0018:ffffc90006427b48 EFLAGS: 00010256 > > RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > RDX: ffff8880211157c0 RSI: ffffffff89dfbd12 RDI: ffff88802c11a018 > > RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003 > > R10: fffff52000c84f5b R11: 0000000000000000 R12: ffffffff92179188 > > R13: ffffc90006427ba0 R14: ffff88801e0f1100 R15: ffff88802c11a000 > > FS: 00007f01fdd51700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007f01fdd30718 CR3: 000000002a3f9000 CR4: 0000000000350ef0 > > Call Trace: > > <TASK> > > vsock_loopback_cancel_pkt+0x1c/0x20 net/vmw_vsock/vsock_loopback.c:48 > > vsock_transport_cancel_pkt net/vmw_vsock/af_vsock.c:1284 [inline] > > vsock_connect+0x852/0xcc0 net/vmw_vsock/af_vsock.c:1426 > > __sys_connect_file+0x153/0x1a0 net/socket.c:2001 > > __sys_connect+0x165/0x1a0 net/socket.c:2018 > > __do_sys_connect net/socket.c:2028 [inline] > > __se_sys_connect net/socket.c:2025 [inline] > > __x64_sys_connect+0x73/0xb0 net/socket.c:2025 > > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > > do_syscall_64+0x39/0xb0 arch/x86/entry/common.c:80 > > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > RIP: 0033:0x7f01fdda0159 > > Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 41 15 00 00 90 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:00007f01fdd51308 EFLAGS: 00000246 ORIG_RAX: 000000000000002a > > RAX: ffffffffffffffda RBX: 00007f01fde28428 RCX: 00007f01fdda0159 > > RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004 > > RBP: 00007f01fde28420 R08: 0000000000000000 R09: 0000000000000000 > > R10: 0000000000000000 R11: 0000000000000246 R12: 00007f01fddf606c > > R13: 0000000000000000 R14: 00007f01fdd51400 R15: 0000000000022000 > > </TASK> > > Modules linked in: > > ---[ end trace 0000000000000000 ]--- > > RIP: 0010:virtio_transport_purge_skbs+0x139/0x4c0 net/vmw_vsock/virtio_transport_common.c:1370 > > Code: 00 00 00 00 fc ff df 48 89 c2 48 89 44 24 28 48 c1 ea 03 48 8d 04 1a 48 89 44 24 10 eb 29 e8 ee 27 a3 f7 48 89 e8 48 c1 e8 03 <80> 3c 18 00 0f 85 a6 02 00 00 49 39 ec 48 8b 55 00 49 89 ef 0f 84 > > RSP: 0018:ffffc90006427b48 EFLAGS: 00010256 > > RAX: 0000000000000000 RBX: dffffc0000000000 RCX: 0000000000000000 > > RDX: ffff8880211157c0 RSI: ffffffff89dfbd12 RDI: ffff88802c11a018 > > RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000003 > > R10: fffff52000c84f5b R11: 0000000000000000 R12: ffffffff92179188 > > R13: ffffc90006427ba0 R14: ffff88801e0f1100 R15: ffff88802c11a000 > > FS: 00007f01fdd51700(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 > > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > CR2: 00007f01fdd30718 CR3: 000000002a3f9000 CR4: 0000000000350ef0 > > ---------------- > > Code disassembly (best guess), 6 bytes skipped: > > 0: df 48 89 fisttps -0x77(%rax) > > 3: c2 48 89 retq $0x8948 > > 6: 44 24 28 rex.R and $0x28,%al > > 9: 48 c1 ea 03 shr $0x3,%rdx > > d: 48 8d 04 1a lea (%rdx,%rbx,1),%rax > > 11: 48 89 44 24 10 mov %rax,0x10(%rsp) > > 16: eb 29 jmp 0x41 > > 18: e8 ee 27 a3 f7 callq 0xf7a3280b > > 1d: 48 89 e8 mov %rbp,%rax > > 20: 48 c1 e8 03 shr $0x3,%rax > > * 24: 80 3c 18 00 cmpb $0x0,(%rax,%rbx,1) <-- trapping instruction > > 28: 0f 85 a6 02 00 00 jne 0x2d4 > > 2e: 49 39 ec cmp %rbp,%r12 > > 31: 48 8b 55 00 mov 0x0(%rbp),%rdx > > 35: 49 89 ef mov %rbp,%r15 > > 38: 0f .byte 0xf > > 39: 84 .byte 0x84 > > > > > > --- > > This report is generated by a bot. It may contain errors. > > See https://goo.gl/tpsmEJ for more information about syzbot. > > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > > > syzbot will keep track of this issue. See: > > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > > syzbot can test patches for this issue, for details see: > > https://goo.gl/tpsmEJ#testing-patches > >
