Re: kernel BUG at include/linux/mm.h:LINE! (5)

[Eric Dumazet]

On 03/04/2019 02:23 PM, syzbot wrote:
> Hello,
> 
> syzbot found the following crash on:
> 
> HEAD commit:ÂÂÂ 9e9322e5d28e selftest/net: Remove duplicate header
> git tree:ÂÂÂÂÂÂ net-next
> console output: https://syzkaller.appspot.com/x/log.txt?x=13516233200000
> kernel config:Â https://syzkaller.appspot.com/x/.config?x=47f2db597668ac40
> dashboard link: https://syzkaller.appspot.com/bug?extid=5013d47539cdd43e7098
> compiler:ÂÂÂÂÂÂ gcc (GCC) 9.0.0 20181231 (experimental)
> syz repro:ÂÂÂÂÂ https://syzkaller.appspot.com/x/repro.syz?x=148763eb200000
> C reproducer:ÂÂ https://syzkaller.appspot.com/x/repro.c?x=1416ff3d200000
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+5013d47539cdd43e7098@xxxxxxxxxxxxxxxxxxxxxxxxx
> 
> flags: 0x1fffc0000000000()
> raw: 01fffc0000000000 ffffea00025f6208 ffff88812fffc878 0000000000000000
> raw: 0000000000000000 0000000000000003 00000000ffffff7f 0000000000000000
> page dumped because: VM_BUG_ON_PAGE(page_ref_count(page) == 0)
> ------------[ cut here ]------------
> kernel BUG at include/linux/mm.h:546!
> invalid opcode: 0000 [#1] PREEMPT SMP KASAN
> CPU: 0 PID: 7872 Comm: syz-executor445 Not tainted 5.0.0-rc7+ #95
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
> RIP: 0010:put_page_testzero include/linux/mm.h:546 [inline]
> RIP: 0010:put_page include/linux/mm.h:992 [inline]
> RIP: 0010:__skb_frag_unref include/linux/skbuff.h:2837 [inline]
> RIP: 0010:skb_release_data+0x5a5/0x7b0 net/core/skbuff.c:571
> Code: f0 fe ff e9 b6 fb ff ff e8 38 b9 01 fc 4c 8d 63 ff e9 c8 fc ff ff e8 2a b9 01 fc 48 c7 c6 80 c2 fe 87 4c 89 e7 e8 bb c6 2a fc <0f> 0b e8 14 b9 01 fc 4d 8d 66 0e 48 b8 00 00 00 00 00 fc ff df 4c
> RSP: 0018:ffff888086a0f708 EFLAGS: 00010293
> RAX: ffff8880a3590440 RBX: ffffea00025dfa34 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff81990662 RDI: ffffea00025dfa38
> RBP: ffff888086a0f770 R08: 000000000000003e R09: ffffed1015d03ef9
> R10: ffffed1015d03ef8 R11: ffff8880ae81f7c7 R12: ffffea00025dfa00
> R13: ffff8880a4398c40 R14: 0000000000000001 R15: dffffc0000000000
> FS:Â 00007fba67236700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
> CS:Â 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fba67235e78 CR3: 0000000099c9f000 CR4: 00000000001406f0
> Call Trace:
> Âskb_release_all+0x4d/0x60 net/core/skbuff.c:631
> Â__kfree_skb+0x16/0x30 net/core/skbuff.c:645
> Âsk_wmem_free_skb include/net/sock.h:1463 [inline]
> Âtcp_write_queue_purge+0x253/0x7d0 net/ipv4/tcp.c:2543
> Âtcp_disconnect+0x402/0x1890 net/ipv4/tcp.c:2583
> Âtcp_close+0xe37/0x10c0 net/ipv4/tcp.c:2384
> Âtls_sk_proto_close+0x40d/0x7a0 net/tls/tls_main.c:291
> Âinet_release+0x105/0x1f0 net/ipv4/af_inet.c:428
> Âinet6_release+0x53/0x80 net/ipv6/af_inet6.c:473
> Â__sock_release+0xd3/0x2b0 net/socket.c:579
> Âsock_close+0x1b/0x30 net/socket.c:1162
> Â__fput+0x2df/0x8d0 fs/file_table.c:278
> Â____fput+0x16/0x20 fs/file_table.c:309
> Âtask_work_run+0x14a/0x1c0 kernel/task_work.c:113
> Âexit_task_work include/linux/task_work.h:22 [inline]
> Âdo_exit+0x92c/0x2fd0 kernel/exit.c:875
> Âdo_group_exit+0x135/0x370 kernel/exit.c:979
> Âget_signal+0x399/0x1d50 kernel/signal.c:2575
> Âdo_signal+0x87/0x1940 arch/x86/kernel/signal.c:816
> Âexit_to_usermode_loop+0x244/0x2c0 arch/x86/entry/common.c:162
> Âprepare_exit_to_usermode arch/x86/entry/common.c:197 [inline]
> Âsyscall_return_slowpath arch/x86/entry/common.c:268 [inline]
> Âdo_syscall_64+0x52d/0x610 arch/x86/entry/common.c:293
> Âentry_SYSCALL_64_after_hwframe+0x49/0xbe
> RIP: 0033:0x447589
> Code: 6e 4d 6f 64 65 00 69 43 75 72 72 4f 66 66 73 00 69 4d 61 78 46 69 6c 65 53 69 7a 65 00 69 4d 61 78 46 69 6c 65 73 00 69 46 69 <6c> 65 4e 75 6d 44 69 67 69 74 73 00 62 44 65 6c 65 74 65 4f 6e 43
> RSP: 002b:00007fba67235d98 EFLAGS: 00000246 ORIG_RAX: 00000000000000ca
> RAX: fffffffffffffe00 RBX: 00000000006ddc68 RCX: 0000000000447589
> RDX: 0000000000000000 RSI: 0000000000000080 RDI: 00000000006ddc68
> RBP: 00000000006ddc60 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000246 R12: 00000000006ddc6c
> R13: 0030656c69662f2e R14: 0000000000000000 R15: 0000000000000000
> Modules linked in:
> ---[ end trace 3c84b12f07d7d40a ]---
> RIP: 0010:put_page_testzero include/linux/mm.h:546 [inline]
> RIP: 0010:put_page include/linux/mm.h:992 [inline]
> RIP: 0010:__skb_frag_unref include/linux/skbuff.h:2837 [inline]
> RIP: 0010:skb_release_data+0x5a5/0x7b0 net/core/skbuff.c:571
> Code: f0 fe ff e9 b6 fb ff ff e8 38 b9 01 fc 4c 8d 63 ff e9 c8 fc ff ff e8 2a b9 01 fc 48 c7 c6 80 c2 fe 87 4c 89 e7 e8 bb c6 2a fc <0f> 0b e8 14 b9 01 fc 4d 8d 66 0e 48 b8 00 00 00 00 00 fc ff df 4c
> RSP: 0018:ffff888086a0f708 EFLAGS: 00010293
> RAX: ffff8880a3590440 RBX: ffffea00025dfa34 RCX: 0000000000000000
> RDX: 0000000000000000 RSI: ffffffff81990662 RDI: ffffea00025dfa38
> RBP: ffff888086a0f770 R08: 000000000000003e R09: ffffed1015d03ef9
> R10: ffffed1015d03ef8 R11: ffff8880ae81f7c7 R12: ffffea00025dfa00
> R13: ffff8880a4398c40 R14: 0000000000000001 R15: dffffc0000000000
> FS:Â 00007fba67236700(0000) GS:ffff8880ae800000(0000) knlGS:0000000000000000
> CS:Â 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00007fba67235e78 CR3: 0000000099c9f000 CR4: 00000000001406f0
> 
> 
> ---
> 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@xxxxxxxxxxxxxxxxx
> 
> syzbot will keep track of this bug report. See:
> https://goo.gl/tpsmEJ#bug-status-tracking for how to communicate with syzbot.
> syzbot can test patches for this bug, for details see:
> https://goo.gl/tpsmEJ#testing-patches

This looks like a TLS issue to me ?

There is a C repro on this bug report (  https://syzkaller.appspot.com/x/repro.c?x=1416ff3d200000 )