general protection fault in llc_ui_autobind

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: af1af6ebca0e Linux 4.14.274
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=137f2cab700000
kernel config: https://syzkaller.appspot.com/x/.config?x=425e8e4e86f35eba
dashboard link: https://syzkaller.appspot.com/bug?extid=90a70acfb24f1d6bf70c
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

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+90a70a...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 1 PID: 16643 Comm: syz-executor.2 Not tainted 4.14.274-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
task: ffff888097662680 task.stack: ffff88809efb8000
RIP: 0010:dev_put include/linux/netdevice.h:3381 [inline]
RIP: 0010:llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320
RSP: 0018:ffff88809efbfcc8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88808dac8280 RCX: ffffc90009af3000
RDX: 00000000000000a8 RSI: ffffffff85d0c563 RDI: 0000000000000540
RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: ffff88809efbfe28 R14: 0000000000000010 R15: ffff8880752735a0
FS: 00007fa715622700(0000) GS:ffff8880ba500000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fa715601718 CR3: 00000000812a3000 CR4: 00000000003406e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
llc_ui_connect+0x4b9/0xab0 net/llc/af_llc.c:500
SYSC_connect net/socket.c:1655 [inline]
SyS_connect+0x1f4/0x240 net/socket.c:1636
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7fa716cad049
RSP: 002b:00007fa715622168 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 00007fa716dbff60 RCX: 00007fa716cad049
RDX: 0000000000000010 RSI: 0000000020000180 RDI: 0000000000000011
RBP: 00007fa716d0708d R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007ffda708ff2f R14: 00007fa715622300 R15: 0000000000022000
Code: 55 ff ff 48 0f ba 73 60 08 45 31 e4 31 ed e8 dd 7c 84 fb 48 8d bd 40 05 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f2 00 00 00 48 8b 85 40 05 00 00 65 ff 08 44
RIP: dev_put include/linux/netdevice.h:3381 [inline] RSP: ffff88809efbfcc8
RIP: llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320 RSP: ffff88809efbfcc8
EXT4-fs (loop3): mounted filesystem without journal. Opts: ,errors=continue
EXT4-fs error (device loop3): ext4_find_dest_de:1834: inode #2: block 16: comm syz-executor.3: bad entry in directory: rec_len is smaller than minimal - offset=0, inode=0, rec_len=0, name_len=0, size=4096
---[ end trace 080a8c44687be9df ]---
----------------
Code disassembly (best guess), 2 bytes skipped:
0: ff 48 0f decl 0xf(%rax)
3: ba 73 60 08 45 mov $0x45086073,%edx
8: 31 e4 xor %esp,%esp
a: 31 ed xor %ebp,%ebp
c: e8 dd 7c 84 fb callq 0xfb847cee
11: 48 8d bd 40 05 00 00 lea 0x540(%rbp),%rdi
18: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1f: fc ff df
22: 48 89 fa mov %rdi,%rdx
25: 48 c1 ea 03 shr $0x3,%rdx
* 29: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2d: 0f 85 f2 00 00 00 jne 0x125
33: 48 8b 85 40 05 00 00 mov 0x540(%rbp),%rax
3a: 65 ff 08 decl %gs:(%rax)
3d: 44 rex.R


---
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[syzbot]

syzbot has found a reproducer for the following issue on:

HEAD commit: af1af6ebca0e Linux 4.14.274
git tree: linux-4.14.y

console output: https://syzkaller.appspot.com/x/log.txt?x=12afee8b700000

kernel config: https://syzkaller.appspot.com/x/.config?x=425e8e4e86f35eba
dashboard link: https://syzkaller.appspot.com/bug?extid=90a70acfb24f1d6bf70c
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=10714357700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=110c8b57700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+90a70a...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:

CPU: 0 PID: 8014 Comm: syz-executor419 Not tainted 4.14.274-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011

task: ffff888099f66680 task.stack: ffff8880b33f8000

RIP: 0010:dev_put include/linux/netdevice.h:3381 [inline]
RIP: 0010:llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320

RSP: 0018:ffff8880b33ffcc8 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff8880b31bf540 RCX: 1ffff110133ecde5
RDX: 00000000000000a8 RSI: ffff888099f66f08 RDI: 0000000000000540

RBP: 0000000000000000 R08: 0000000000000001 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000

R13: ffff8880b33ffe28 R14: 0000000000000010 R15: ffff8880a87c9520
FS: 00005555556c0300(0000) GS:ffff8880ba400000(0000) knlGS:0000000000000000

CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033

CR2: 0000000020000184 CR3: 00000000ac051000 CR4: 00000000003406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
llc_ui_connect+0x4b9/0xab0 net/llc/af_llc.c:500
SYSC_connect net/socket.c:1655 [inline]
SyS_connect+0x1f4/0x240 net/socket.c:1636
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

RIP: 0033:0x7f251ee52009
RSP: 002b:00007ffe81751278 EFLAGS: 00000246 ORIG_RAX: 000000000000002a
RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f251ee52009
RDX: 0000000000000010 RSI: 0000000020000180 RDI: 0000000000000003
RBP: 00007f251ee15ff0 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007f251ee16080
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Code: 55 ff ff 48 0f ba 73 60 08 45 31 e4 31 ed e8 dd 7c 84 fb 48 8d bd 40 05 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 f2 00 00 00 48 8b 85 40 05 00 00 65 ff 08 44

RIP: dev_put include/linux/netdevice.h:3381 [inline] RSP: ffff8880b33ffcc8
RIP: llc_ui_autobind.isra.0+0x26b/0x390 net/llc/af_llc.c:320 RSP: ffff8880b33ffcc8
---[ end trace 5d7a90ab55e29fff ]---