On 3/1/20 5:33 PM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: fd786fb1 net: convert suitable drivers to use phy_do_ioctl.. > git tree: net-next > console output: https://syzkaller.appspot.com/x/log.txt?x=14e9726ee00000 > kernel config: https://syzkaller.appspot.com/x/.config?x=7f93900a7904130d > dashboard link: https://syzkaller.appspot.com/bug?extid=dd803bc0e8adf0003261 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=12af9369e00000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=10583d76e00000 > > The bug was bisected to: > > commit 14215108a1fd7e002c0a1f9faf8fbaf41fdda50d > Author: Cong Wang <xiyou.wangcong@xxxxxxxxx> > Date: Thu Feb 21 05:37:42 2019 +0000 > > net_sched: initialize net pointer inside tcf_exts_init() > > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=175b66bee00000 > final crash: https://syzkaller.appspot.com/x/report.txt?x=14db66bee00000 > console output: https://syzkaller.appspot.com/x/log.txt?x=10db66bee00000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+dd803bc0e8adf0003261@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 14215108a1fd ("net_sched: initialize net pointer inside tcf_exts_init()") > > RBP: 0000000000000000 R08: 0000000000000002 R09: 00000000bb1414ac > R10: 0000000000000000 R11: 0000000000000246 R12: ffffffffffffffff > R13: 0000000000000009 R14: 0000000000000000 R15: 0000000000000000 > ------------[ cut here ]------------ > refcount_t: underflow; use-after-free. > WARNING: CPU: 1 PID: 9577 at lib/refcount.c:28 refcount_warn_saturate+0x1dc/0x1f0 lib/refcount.c:28 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 1 PID: 9577 Comm: syz-executor327 Not tainted 5.5.0-rc6-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+0x197/0x210 lib/dump_stack.c:118 > panic+0x2e3/0x75c kernel/panic.c:221 > __warn.cold+0x2f/0x3e kernel/panic.c:582 > report_bug+0x289/0x300 lib/bug.c:195 > fixup_bug arch/x86/kernel/traps.c:174 [inline] > fixup_bug arch/x86/kernel/traps.c:169 [inline] > do_error_trap+0x11b/0x200 arch/x86/kernel/traps.c:267 > do_invalid_op+0x37/0x50 arch/x86/kernel/traps.c:286 > invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1027 > RIP: 0010:refcount_warn_saturate+0x1dc/0x1f0 lib/refcount.c:28 > Code: e9 d8 fe ff ff 48 89 df e8 c1 f8 16 fe e9 85 fe ff ff e8 a7 77 d8 fd 48 c7 c7 e0 44 71 88 c6 05 9e 86 db 06 01 e8 93 27 a9 fd <0f> 0b e9 ac fe ff ff 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 55 48 > RSP: 0018:ffffc9000c067b00 EFLAGS: 00010282 > RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffffffff815e5dd6 RDI: fffff5200180cf52 > RBP: ffffc9000c067b10 R08: ffff8880a8630340 R09: ffffed1015d26621 > R10: ffffed1015d26620 R11: ffff8880ae933107 R12: 0000000000000003 > R13: ffff888090256000 R14: ffff8880a7e5c040 R15: ffff8880a7e5c044 > refcount_sub_and_test include/linux/refcount.h:261 [inline] > refcount_dec_and_test include/linux/refcount.h:281 [inline] > put_net include/net/net_namespace.h:259 [inline] > __sk_destruct+0x6d8/0x7f0 net/core/sock.c:1723 > sk_destruct+0xd5/0x110 net/core/sock.c:1739 > __sk_free+0xfb/0x3f0 net/core/sock.c:1750 > sk_free+0x83/0xb0 net/core/sock.c:1761 > sock_put include/net/sock.h:1719 [inline] > __tun_detach+0xbe0/0x1150 drivers/net/tun.c:728 > tun_detach drivers/net/tun.c:740 [inline] > tun_chr_close+0xe0/0x180 drivers/net/tun.c:3455 > __fput+0x2ff/0x890 fs/file_table.c:280 > ____fput+0x16/0x20 fs/file_table.c:313 > task_work_run+0x145/0x1c0 kernel/task_work.c:113 > exit_task_work include/linux/task_work.h:22 [inline] > do_exit+0xba9/0x2f50 kernel/exit.c:801 > do_group_exit+0x135/0x360 kernel/exit.c:899 > __do_sys_exit_group kernel/exit.c:910 [inline] > __se_sys_exit_group kernel/exit.c:908 [inline] > __x64_sys_exit_group+0x44/0x50 kernel/exit.c:908 > do_syscall_64+0xfa/0x790 arch/x86/entry/common.c:294 > entry_SYSCALL_64_after_hwframe+0x49/0xbe > RIP: 0033:0x441a48 > Code: Bad RIP value. > RSP: 002b:00007fffe55809a8 EFLAGS: 00000246 ORIG_RAX: 00000000000000e7 > RAX: ffffffffffffffda RBX: 0000000000000001 RCX: 0000000000441a48 > RDX: 0000000000000001 RSI: 000000000000003c RDI: 0000000000000001 > RBP: 00000000004c8430 R08: 00000000000000e7 R09: ffffffffffffffd0 > R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001 > R13: 00000000006dba80 R14: 0000000000000000 R15: 0000000000000000 > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > > --- > This bug 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 bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > Hmmm... maybe this patch would fix it ? diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h index a972244ab1931a2fd52a41efa4f7a6cd78d8746a..6e258a6c1328e38a757d9711f4116a6672995b8f 100644 --- a/include/net/pkt_cls.h +++ b/include/net/pkt_cls.h @@ -206,11 +206,12 @@ static inline int tcf_exts_init(struct tcf_exts *exts, struct net *net, #ifdef CONFIG_NET_CLS_ACT exts->type = 0; exts->nr_actions = 0; - exts->net = net; + exts->net = NULL; exts->actions = kcalloc(TCA_ACT_MAX_PRIO, sizeof(struct tc_action *), GFP_KERNEL); if (!exts->actions) return -ENOMEM; + exts->net = net; #endif exts->action = action; exts->police = police;
