Re: BUG: unable to handle kernel paging request in compat_copy_entries

[Paolo Abeni]

On Mon, 2018-03-05 at 00:21 -0800, syzbot wrote:
> Hello,
> 
> syzbot hit the following crash on upstream commit
> 5fbdefcf685defd8bc5a8f37b17538d25c58d77a (Fri Mar 2 21:05:20 2018 +0000)
> Merge branch 'parisc-4.16-1' of  
> git://git.kernel.org/pub/scm/linux/kernel/git/deller/parisc-linux
> 
> So far this crash happened 5 times on upstream.
> syzkaller reproducer is attached.
> Raw console output is attached.
> compiler: gcc (GCC) 7.1.1 20170620
> .config is attached.
> user-space arch: i386
> 
> IMPORTANT: if you fix the bug, please add the following tag to the commit:
> Reported-by: syzbot+5705ba91388d7bc30828@xxxxxxxxxxxxxxxxxxxxxxxxx
> It will help syzbot understand when the bug is fixed. See footer for  
> details.
> If you forward the report, please keep this part and the footer.
> 
> audit: type=1400 audit(1520098078.492:8): avc:  denied  { map } for   
> pid=4239 comm="syz-execprog" path="/root/syzkaller-shm255959590" dev="sda1"  
> ino=16482 scontext=unconfined_u:system_r:insmod_t:s0-s0:c0.c1023  
> tcontext=unconfined_u:object_r:file_t:s0 tclass=file permissive=1
> IPVS: ftp: loaded support on port[0] = 21
> BUG: unable to handle kernel paging request at ffffc90001819e4f
> IP: ebt_size_mwt net/bridge/netfilter/ebtables.c:2037 [inline]
> IP: size_entry_mwt net/bridge/netfilter/ebtables.c:2122 [inline]
> IP: compat_copy_entries+0x49f/0x1050 net/bridge/netfilter/ebtables.c:2160
> PGD 1dad2f067 P4D 1dad2f067 PUD 1dad30067 PMD 1b2408067 PTE 0
> Oops: 0000 [#1] SMP KASAN
> Dumping ftrace buffer:
>     (ftrace buffer empty)
> Modules linked in:
> CPU: 1 PID: 4249 Comm: syz-executor0 Not tainted 4.16.0-rc3+ #248
> Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS  
> Google 01/01/2011
> RIP: 0010:ebt_size_mwt net/bridge/netfilter/ebtables.c:2037 [inline]
> RIP: 0010:size_entry_mwt net/bridge/netfilter/ebtables.c:2122 [inline]
> RIP: 0010:compat_copy_entries+0x49f/0x1050  
> net/bridge/netfilter/ebtables.c:2160
> RSP: 0018:ffff8801b34bf7e8 EFLAGS: 00010246
> RAX: 000000000000000a RBX: ffff8801b34bf9d4 RCX: ffffc90001819e4f
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff8801b34bf9d8
> RBP: ffff8801b34bf968 R08: 0000000000000000 R09: 0000000000000000
> R10: ffffffff88613340 R11: 0000000000000001 R12: 000000000000ee5f
> R13: dffffc0000000000 R14: ffff8801b34bf9c8 R15: ffffc90001819e2f
> FS:  0000000000000000(0000) GS:ffff8801db300000(0063) knlGS:00000000085b9900
> CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
> CR2: ffffc90001819e4f CR3: 00000001b2bd7003 CR4: 00000000001606e0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> Call Trace:
>   compat_do_replace+0x398/0x7c0 net/bridge/netfilter/ebtables.c:2249
>   compat_do_ebt_set_ctl+0x22a/0x2d0 net/bridge/netfilter/ebtables.c:2330
>   compat_nf_sockopt net/netfilter/nf_sockopt.c:144 [inline]
>   compat_nf_setsockopt+0x88/0x130 net/netfilter/nf_sockopt.c:156
>   compat_ip_setsockopt+0x8b/0xd0 net/ipv4/ip_sockglue.c:1285
>   inet_csk_compat_setsockopt+0x95/0x120 net/ipv4/inet_connection_sock.c:1041
>   compat_tcp_setsockopt+0x3d/0x70 net/ipv4/tcp.c:2916
>   compat_sock_common_setsockopt+0xb2/0x140 net/core/sock.c:2986
>   C_SYSC_setsockopt net/compat.c:403 [inline]
>   compat_SyS_setsockopt+0x17c/0x410 net/compat.c:386
>   do_syscall_32_irqs_on arch/x86/entry/common.c:330 [inline]
>   do_fast_syscall_32+0x3ec/0xf9f arch/x86/entry/common.c:392
>   entry_SYSENTER_compat+0x70/0x7f arch/x86/entry/entry_64_compat.S:139
> RIP: 0023:0xf7fbbc99
> RSP: 002b:00000000ffd5ab8c EFLAGS: 00000286 ORIG_RAX: 000000000000016e
> RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 0000000000000000
> RDX: 0000000000000080 RSI: 0000000020000280 RDI: 0000000000000208
> RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
> R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
> R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
> Code: 8d 4f 20 48 89 c8 48 89 8d c8 fe ff ff 48 c1 e8 03 42 0f b6 14 28 48  
> 89 c8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 b2 0a 00 00 <45> 8b 67 20  
> 44 39 a5 04 ff ff ff 0f 82 bd 08 00 00 e8 cb 52 56
> RIP: ebt_size_mwt net/bridge/netfilter/ebtables.c:2037 [inline] RSP:  
> ffff8801b34bf7e8
> RIP: size_entry_mwt net/bridge/netfilter/ebtables.c:2122 [inline] RSP:  
> ffff8801b34bf7e8
> RIP: compat_copy_entries+0x49f/0x1050 net/bridge/netfilter/ebtables.c:2160  
> RSP: ffff8801b34bf7e8
> CR2: ffffc90001819e4f
> ---[ end trace cf111332eb971f16 ]---
> 
> 
> ---
> This bug is generated by a dumb bot. It may contain errors.
> See https://goo.gl/tpsmEJ for details.
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#syz fix: netfilter: ebtables: add CONFIG_COMPAT support