Hi Hillf, >> syzbot found the following crash on: >> >> HEAD commit: fb279f4e Merge branch 'i2c/for-current-fixed' of git://git.. >> git tree: upstream >> console output: https://syzkaller.appspot.com/x/log.txt?x=168c481de00000 >> kernel config: https://syzkaller.appspot.com/x/.config?x=8b13b05f0e61d957 >> dashboard link: https://syzkaller.appspot.com/bug?extid=4496e82090657320efc6 >> compiler: clang version 10.0.0 (https://github.com/llvm/llvm-project/ c2443155a0fb245c8f17f2c1c72b6ea391e86e81) >> >> Unfortunately, I don't have any reproducer for this crash yet. >> >> IMPORTANT: if you fix the bug, please add the following tag to the commit: >> Reported-by: syzbot+4496e82090657320efc6@xxxxxxxxxxxxxxxxxxxxxxxxx >> >> ------------[ cut here ]------------ >> ODEBUG: free active (active state 0) object type: timer_list hint: rfcomm_dlc_timeout+0x0/0xc0 net/bluetooth/rfcomm/core.c:300 >> WARNING: CPU: 0 PID: 9181 at lib/debugobjects.c:488 debug_print_object lib/debugobjects.c:485 [inline] >> WARNING: CPU: 0 PID: 9181 at lib/debugobjects.c:488 __debug_check_no_obj_freed lib/debugobjects.c:967 [inline] >> WARNING: CPU: 0 PID: 9181 at lib/debugobjects.c:488 debug_check_no_obj_freed+0x45c/0x640 lib/debugobjects.c:998 >> Kernel panic - not syncing: panic_on_warn set ... >> CPU: 0 PID: 9181 Comm: syz-executor.3 Not tainted 5.6.0-rc3-syzkaller #0 >> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 >> Call Trace: >> __dump_stack lib/dump_stack.c:77 [inline] >> dump_stack+0x1e9/0x30e lib/dump_stack.c:118 >> panic+0x264/0x7a0 kernel/panic.c:221 >> __warn+0x209/0x210 kernel/panic.c:582 >> report_bug+0x1ac/0x2d0 lib/bug.c:195 >> fixup_bug arch/x86/kernel/traps.c:174 [inline] >> do_error_trap+0xca/0x1c0 arch/x86/kernel/traps.c:267 >> do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:286 >> invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 >> RIP: 0010:debug_print_object lib/debugobjects.c:485 [inline] >> RIP: 0010:__debug_check_no_obj_freed lib/debugobjects.c:967 [inline] >> RIP: 0010:debug_check_no_obj_freed+0x45c/0x640 lib/debugobjects.c:998 >> Code: 74 08 4c 89 f7 e8 64 2d 18 fe 4d 8b 06 48 c7 c7 53 10 d1 88 48 c7 c6 0f 01 cf 88 48 89 da 89 e9 4d 89 f9 31 c0 e8 c4 cd ae fd <0f> 0b 48 ba 00 00 00 00 00 fc ff df ff 05 c6 39 b1 05 48 8b 5c 24 >> RSP: 0018:ffffc90001907c88 EFLAGS: 00010046 >> RAX: 72f8f847df918a00 RBX: ffffffff88d4edca RCX: 0000000000040000 >> RDX: ffffc90011373000 RSI: 0000000000013ee9 RDI: 0000000000013eea >> RBP: 0000000000000000 R08: ffffffff815e1276 R09: ffffed1015d04592 >> R10: ffffed1015d04592 R11: 0000000000000000 R12: ffff88808ea6fbac >> R13: ffffffff8b592e40 R14: ffffffff890ddc78 R15: ffffffff873dcc50 >> kfree+0xfc/0x220 mm/slab.c:3756 >> rfcomm_dlc_put include/net/bluetooth/rfcomm.h:258 [inline] >> __rfcomm_create_dev net/bluetooth/rfcomm/tty.c:417 [inline] >> rfcomm_create_dev net/bluetooth/rfcomm/tty.c:486 [inline] >> rfcomm_dev_ioctl+0xe37/0x2340 net/bluetooth/rfcomm/tty.c:588 >> rfcomm_sock_ioctl+0x79/0xa0 net/bluetooth/rfcomm/sock.c:902 >> sock_do_ioctl+0x7b/0x260 net/socket.c:1053 >> sock_ioctl+0x4aa/0x690 net/socket.c:1204 >> vfs_ioctl fs/ioctl.c:47 [inline] >> ksys_ioctl fs/ioctl.c:763 [inline] >> __do_sys_ioctl fs/ioctl.c:772 [inline] >> __se_sys_ioctl+0xf9/0x160 fs/ioctl.c:770 >> do_syscall_64+0xf3/0x1b0 arch/x86/entry/common.c:294 >> entry_SYSCALL_64_after_hwframe+0x49/0xbe >> > > No need to put dlc as it's not held in rfcomm_dlc_exists(). > > --- a/net/bluetooth/rfcomm/tty.c > +++ b/net/bluetooth/rfcomm/tty.c > @@ -413,10 +413,8 @@ static int __rfcomm_create_dev(struct so > dlc = rfcomm_dlc_exists(&req.src, &req.dst, req.channel); > if (IS_ERR(dlc)) > return PTR_ERR(dlc); > - else if (dlc) { > - rfcomm_dlc_put(dlc); > + if (dlc) > return -EBUSY; > - } > dlc = rfcomm_dlc_alloc(GFP_KERNEL); > if (!dlc) > return -ENOMEM; > looks like this has been there since 2014 and nobody trigged it yet. Care to send a patch that I can apply. Regards Marcel
