> Hello, > > syzbot found the following issue on: > > HEAD commit: 9c1bec9c0b08 Merge tag 'linux-kselftest-fixes-6.3-rc3' of .. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=17285724c80000 > kernel config: https://syzkaller.appspot.com/x/.config?x=6c84f77790aba2eb > dashboard link: https://syzkaller.appspot.com/bug?extid=a7492efaa5d61b51db23 > 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=13c9f8a4c80000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10e8fe2cc80000 > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/eee5724f97b4/disk-9c1bec9c.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/00ee10c4bc28/vmlinux-9c1bec9c.xz > kernel image: https://storage.googleapis.com/syzbot-assets/42cf9c3e67cd/bzImage-9c1bec9c.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+a7492efaa5d61b51db23@xxxxxxxxxxxxxxxxxxxxxxxxx > > ------------[ cut here ]------------ > refcount_t: addition on 0; use-after-free. > WARNING: CPU: 0 PID: 46 at lib/refcount.c:25 refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25 > Modules linked in: > CPU: 0 PID: 46 Comm: kworker/u4:3 Not tainted 6.3.0-rc2-syzkaller-00050-g9c1bec9c0b08 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/02/2023 > Workqueue: qrtr_ns_handler qrtr_ns_worker > RIP: 0010:refcount_warn_saturate+0x17c/0x1f0 lib/refcount.c:25 > Code: 0a 31 ff 89 de e8 64 17 73 fd 84 db 0f 85 2e ff ff ff e8 47 1b 73 fd 48 c7 c7 e0 6a a6 8a c6 05 5d 73 52 0a 01 e8 e4 94 3b fd <0f> 0b e9 0f ff ff ff e8 28 1b 73 fd 0f b6 1d 47 73 52 0a 31 ff 89 > RSP: 0018:ffffc90000b779d8 EFLAGS: 00010086 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: ffff888017d61d40 RSI: ffffffff814b6037 RDI: 0000000000000001 > RBP: ffff88802717ec98 R08: 0000000000000001 R09: 0000000000000000 > R10: 0000000000000000 R11: 0000000000000000 R12: ffff888145178000 > R13: ffff88802717ec00 R14: ffff8880280b1030 R15: ffff8880280b1034 > FS: 0000000000000000(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007ffdb2009388 CR3: 0000000029dad000 CR4: 00000000003506f0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > <TASK> > __refcount_add include/linux/refcount.h:199 [inline] > __refcount_inc include/linux/refcount.h:250 [inline] > refcount_inc include/linux/refcount.h:267 [inline] > kref_get include/linux/kref.h:45 [inline] > qrtr_node_acquire net/qrtr/af_qrtr.c:202 [inline] > qrtr_node_lookup net/qrtr/af_qrtr.c:398 [inline] > qrtr_send_resume_tx net/qrtr/af_qrtr.c:1003 [inline] > qrtr_recvmsg+0x85f/0x990 net/qrtr/af_qrtr.c:1070 > sock_recvmsg_nosec net/socket.c:1017 [inline] > sock_recvmsg+0xe2/0x160 net/socket.c:1038 > qrtr_ns_worker+0x170/0x1700 net/qrtr/ns.c:688 > process_one_work+0x991/0x15c0 kernel/workqueue.c:2390 > worker_thread+0x669/0x1090 kernel/workqueue.c:2537 > kthread+0x2e8/0x3a0 kernel/kthread.c:376 > ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308 > </TASK> > It occurs in the concurrent scenario of qrtr_recvmsg() and qrtr_endpoint_unregister() as following: cpu0 cpu1 qrtr_recvmsg qrtr_endpoint_unregister qrtr_send_resume_tx qrtr_node_release qrtr_node_lookup mutex_lock(&qrtr_node_lock) spin_lock_irqsave(&qrtr_nodes_lock, ) refcount_dec_and_test(&node->ref) [node->ref == 0] qrtr_node_acquire [node != NULL] spin_lock_irqsave(&qrtr_nodes_lock, ) kref_get(&node->ref) [WARNING] __qrtr_node_release mutex_unlock(&qrtr_node_lock) and I will give a fix later. > > --- > 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 > . >
