general protection fault in rxrpc_get_skb

[syzbot]

Hello,

syzbot found the following crash on:

HEAD commit: 01fd1694 Linux 4.14.141
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=105c2946600000
kernel config: https://syzkaller.appspot.com/x/.config?x=62c9b69e1b2adda9
dashboard link: https://syzkaller.appspot.com/bug?extid=f1df0947aed2a0500e3d
compiler: gcc (GCC) 9.0.0 20181231 (experimental)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1054fa9e600000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f1df09...@syzkaller.appspotmail.com

kasan: CONFIG_KASAN_INLINE enabled
kasan: GPF could be caused by NULL-ptr deref or user memory access
kobject: 'loop1' (ffff8880a4a10e60): fill_kobj_path: path
= '/devices/virtual/block/loop1'
general protection fault: 0000 [#1] PREEMPT SMP KASAN
Modules linked in:
CPU: 0 PID: 7000 Comm: kworker/0:0 Not tainted 4.14.141 #37
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS
Google 01/01/2011
Workqueue: krxrpcd rxrpc_process_call
task: ffff888094efe4c0 task.stack: ffff888075430000
RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:27 [inline]
RIP: 0010:refcount_read include/linux/refcount.h:42 [inline]
RIP: 0010:rxrpc_get_skb+0x65/0x360 net/rxrpc/skbuff.c:52
RSP: 0018:ffff888075437c28 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffff888094efed40
RDX: 000000000000001c RSI: 000000000000000a RDI: 0000000000000000
RBP: ffff888075437c68 R08: 0000000000004d2f R09: ffffffff88ca5df8
R10: ffff888094efed90 R11: ffff888094efe4c0 R12: 0000000000000000
R13: 0000000000000000 R14: 00000000000000e4 R15: 000000000000000a
FS: 0000000000000000(0000) GS:ffff8880aee00000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff387fc020 CR3: 000000007b25f000 CR4: 00000000001406f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
rxrpc_resend net/rxrpc/call_event.c:319 [inline]
rxrpc_process_call+0x555/0x1169 net/rxrpc/call_event.c:407
process_one_work+0x863/0x1600 kernel/workqueue.c:2114
worker_thread+0x5d9/0x1050 kernel/workqueue.c:2248
kthread+0x319/0x430 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: c0 a0 99 c2 89 4c 0f 46 f0 e8 b8 5b c5 fb f0 45 0f c1 2e 4c 8d b3 e4
00 00 00 48 b8 00 00 00 00 00 fc ff df 4c 89 f2 48 c1 ea 03 <0f> b6 14 02
4c 89 f0 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85
RIP: __read_once_size include/linux/compiler.h:183 [inline] RSP:
ffff888075437c28
RIP: atomic_read arch/x86/include/asm/atomic.h:27 [inline] RSP:
ffff888075437c28
RIP: refcount_read include/linux/refcount.h:42 [inline] RSP:
ffff888075437c28
RIP: rxrpc_get_skb+0x65/0x360 net/rxrpc/skbuff.c:52 RSP: ffff888075437c28
---[ end trace e222a7f3215c037e ]---


---
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[syzbot]

syzbot has found a reproducer for the following crash on:

HEAD commit: 12cd844a Linux 4.14.173
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=1246cd55e00000
kernel config: https://syzkaller.appspot.com/x/.config?x=8a9d0602a0f7791e

dashboard link: https://syzkaller.appspot.com/bug?extid=f1df0947aed2a0500e3d
compiler: gcc (GCC) 9.0.0 20181231 (experimental)

syz repro: https://syzkaller.appspot.com/x/repro.syz?x=167eda1de00000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=159e8fdde00000

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: syzbot+f1df09...@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: 24 Comm: kworker/0:1 Not tainted 4.14.173-syzkaller #0

Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Workqueue: krxrpcd rxrpc_process_call

task: ffff8880a9a36640 task.stack: ffff8880a9a40000

RIP: 0010:__read_once_size include/linux/compiler.h:183 [inline]
RIP: 0010:atomic_read arch/x86/include/asm/atomic.h:27 [inline]
RIP: 0010:refcount_read include/linux/refcount.h:42 [inline]

RIP: 0010:rxrpc_get_skb+0x5e/0x350 net/rxrpc/skbuff.c:52
RSP: 0018:ffff8880a9a47c50 EFLAGS: 00010203
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 000000000000001c RSI: 000000000000000a RDI: 00000000000000e4
RBP: 000000000000000a R08: 0000000000004897 R09: ffffffff8a07fd38
R10: ffff8880a9a36f10 R11: ffff8880a9a36640 R12: 0000000000000000
R13: ffff88808f2f1a50 R14: ffffffff8b04e520 R15: ffff88808f2f1918
FS: 0000000000000000(0000) GS:ffff8880aea00000(0000) knlGS:0000000000000000

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

CR2: 0000000000000000 CR3: 000000009ea29000 CR4: 00000000001406f0

DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
rxrpc_resend net/rxrpc/call_event.c:319 [inline]

rxrpc_process_call+0x54f/0x1135 net/rxrpc/call_event.c:407
process_one_work+0x813/0x1540 kernel/workqueue.c:2114
worker_thread+0x5d1/0x1070 kernel/workqueue.c:2248
kthread+0x30d/0x420 kernel/kthread.c:232
ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:404
Code: c0 e0 e4 04 8b 4c 0f 46 f0 e8 cf 8d 9d fb f0 45 0f c1 26 48 8d bb e4 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <0f> b6 14 02 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85
RIP: __read_once_size include/linux/compiler.h:183 [inline] RSP: ffff8880a9a47c50
RIP: atomic_read arch/x86/include/asm/atomic.h:27 [inline] RSP: ffff8880a9a47c50
RIP: refcount_read include/linux/refcount.h:42 [inline] RSP: ffff8880a9a47c50
RIP: rxrpc_get_skb+0x5e/0x350 net/rxrpc/skbuff.c:52 RSP: ffff8880a9a47c50
---[ end trace 204afccabccf6962 ]---