Hello, syzbot found the following issue on:
HEAD commit: 581cb3a2 Merge tag 'f2fs-for-5.9-rc5' of git://git.kernel... git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=17796c01900000 kernel config: https://syzkaller.appspot.com/x/.config?x=a9075b36a6ae26c9 dashboard link: https://syzkaller.appspot.com/bug?extid=7e016eb6104c62c4ac86 compiler: gcc (GCC) 10.1.0-syz 20200507 Unfortunately, I don't have any reproducer for this issue yet. IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+7e016eb6104c62c4a...@syzkaller.appspotmail.com ------------[ cut here ]------------ refcount_t: underflow; use-after-free. WARNING: CPU: 0 PID: 455 at lib/refcount.c:28 refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28 Kernel panic - not syncing: panic_on_warn set ... CPU: 0 PID: 455 Comm: syz-executor.5 Not tainted 5.9.0-rc4-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+0x198/0x1fd lib/dump_stack.c:118 panic+0x347/0x7c0 kernel/panic.c:231 __warn.cold+0x20/0x46 kernel/panic.c:600 report_bug+0x1bd/0x210 lib/bug.c:198 handle_bug+0x38/0x90 arch/x86/kernel/traps.c:234 exc_invalid_op+0x14/0x40 arch/x86/kernel/traps.c:254 asm_exc_invalid_op+0x12/0x20 arch/x86/include/asm/idtentry.h:536 RIP: 0010:refcount_warn_saturate+0x1d1/0x1e0 lib/refcount.c:28 Code: e9 db fe ff ff 48 89 df e8 5c dd 18 fe e9 8a fe ff ff e8 f2 d6 d8 fd 48 c7 c7 60 dc 93 88 c6 05 bd 0c 12 07 01 e8 e1 d7 a9 fd <0f> 0b e9 af fe ff ff 0f 1f 84 00 00 00 00 00 41 56 41 55 41 54 55 RSP: 0018:ffffc900118af8a8 EFLAGS: 00010286 RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000040000 RSI: ffffffff815db9a7 RDI: fffff52002315f07 RBP: 0000000000000003 R08: 0000000000000001 R09: ffff8880ae6318e7 R10: 0000000000000000 R11: 0000000035353454 R12: ffff888000101c84 R13: ffff888000101d38 R14: dffffc0000000000 R15: fffffbfff151600c refcount_sub_and_test include/linux/refcount.h:274 [inline] refcount_dec_and_test include/linux/refcount.h:294 [inline] pde_put+0x178/0x1e0 fs/proc/generic.c:659 remove_proc_entry+0x1de/0x460 fs/proc/generic.c:703 ipmr_net_exit+0x75/0x100 net/ipv4/ipmr.c:3089 ops_exit_list+0xb0/0x160 net/core/net_namespace.c:186 setup_net+0x502/0x850 net/core/net_namespace.c:364 copy_net_ns+0x2cf/0x5e0 net/core/net_namespace.c:482 create_new_namespaces+0x3f6/0xb10 kernel/nsproxy.c:110 copy_namespaces+0x385/0x470 kernel/nsproxy.c:179 copy_process+0x294b/0x6920 kernel/fork.c:2072 _do_fork+0xe8/0xb10 kernel/fork.c:2428 __do_sys_clone+0xc8/0x110 kernel/fork.c:2545 do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46 entry_SYSCALL_64_after_hwframe+0x44/0xa9 RIP: 0033:0x45d5b9 Code: 5d b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 00 66 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 0f 83 2b b4 fb ff c3 66 2e 0f 1f 84 00 00 00 00 RSP: 002b:00007f2e23071c78 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 0000000000001fc0 RCX: 000000000045d5b9 RDX: 9999999999999999 RSI: 0000000000000000 RDI: 00000000e1004d7c RBP: 000000000118cf90 R08: ffffffffffffffff R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 000000000118cf4c R13: 000000000169fb6f R14: 00007f2e230729c0 R15: 000000000118cf4c Kernel Offset: disabled Rebooting in 86400 seconds.. --- 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 syzkal...@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot.