BUG: unable to handle kernel paging request in tcp_retransmit_timer

[Wei Chen]

Dear Linux Developer,

Recently when using our tool to fuzz kernel, the following crash was triggered:

HEAD commit: 64570fbc14f8 Linux 5.15-rc5
git tree: upstream
compiler: gcc 8.0.1
console output:
https://drive.google.com/file/d/1wVTAdDoOo8KqTaGm1v8SaKuv1V8Pt9qs/view?usp=share_link
kernel config: https://drive.google.com/file/d/1uDOeEYgJDcLiSOrx9W8v2bqZ6uOA_55t/view?usp=share_link

Unfortunately, I don't have any reproducer for this crash yet.

IMPORTANT: if you fix the bug, please add the following tag to the commit:
Reported-by: Wei Chen <harperchen1110@xxxxxxxxx>

BUG: unable to handle page fault for address: ffffe8ff3fa5f268
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 983f067 P4D 983f067 PUD afce067 PMD 4e244067 PTE 0
Oops: 0002 [#1] PREEMPT SMP
CPU: 0 PID: 6544 Comm: syz-fuzzer Not tainted 5.15.0-rc5 #1
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
rel-1.13.0-48-gd9c812dda519-prebuilt.qemu.org 04/01/2014
RIP: 0010:tcp_retransmit_timer+0x4c5/0x1540
Code: 31 e7 ff ff e9 65 fd ff ff e8 b7 75 3c fd 48 c7 c7 26 1c ee 85
e8 8b fa bc 00 48 8b 43 30 bf 1f 00 00 00 48 8b 80 58 02 00 00 <65> 48
ff 80 40 01 00 00 44 0f b6 73 12 48 8b 43 30 44 89 f6 48 89
RSP: 0000:ffffc90000807cc0 EFLAGS: 00010202
RAX: 0000607ec1e5f128 RBX: ffff8880156c0000 RCX: ffff888011480000
RDX: 0000000000000000 RSI: 0000000000000101 RDI: 000000000000001f
RBP: ffff8880156c0120 R08: ffffffff8400fda9 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000080000001 R12: 0000000080000001
R13: ffff88810cd1b280 R14: ffff888029b5f400 R15: ffff8880156c0278
FS:  000000c000030c90(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffe8ff3fa5f268 CR3: 0000000015c0b000 CR4: 00000000003506f0
Call Trace:
 tcp_write_timer_handler+0x132/0x420
 tcp_write_timer+0x179/0x230
 call_timer_fn+0xe8/0x510
 run_timer_softirq+0x423/0xa40
 __do_softirq+0xe2/0x56b
 irq_exit_rcu+0xb6/0xf0
 sysvec_apic_timer_interrupt+0x52/0xc0
 asm_sysvec_apic_timer_interrupt+0x12/0x20
RIP: 0033:0x415543
Code: 48 8b 1d a0 e8 76 01 84 03 48 8b 14 d3 48 85 d2 74 1d 48 89 c3
48 c1 e8 0d 48 25 ff 1f 00 00 48 8b 8c c2 00 00 20 00 48 89 d8 <e9> 6c
fe ff ff 31 c9 e9 65 fe ff ff cc cc cc cc cc cc cc cc cc cc
RSP: 002b:000000c00003de70 EFLAGS: 00000202
RAX: 000000c004cc8600 RBX: 000000c004cc8600 RCX: 00007f27b2e23400
RDX: 00007f27b2e3b000 RSI: 0000000000000001 RDI: 00000000000dcf40
RBP: 000000c00003de98 R08: 00007f27b303afff R09: 000000c004beb6c0
R10: 000000c000021e98 R11: 0000000000000008 R12: 000000c004cc8600
R13: 000000c000001200 R14: 0000000000c4de75 R15: 0000000000000000
Modules linked in:
CR2: ffffe8ff3fa5f268
---[ end trace 8795388675688c1b ]---
RIP: 0010:tcp_retransmit_timer+0x4c5/0x1540
Code: 31 e7 ff ff e9 65 fd ff ff e8 b7 75 3c fd 48 c7 c7 26 1c ee 85
e8 8b fa bc 00 48 8b 43 30 bf 1f 00 00 00 48 8b 80 58 02 00 00 <65> 48
ff 80 40 01 00 00 44 0f b6 73 12 48 8b 43 30 44 89 f6 48 89
RSP: 0000:ffffc90000807cc0 EFLAGS: 00010202
RAX: 0000607ec1e5f128 RBX: ffff8880156c0000 RCX: ffff888011480000
RDX: 0000000000000000 RSI: 0000000000000101 RDI: 000000000000001f
RBP: ffff8880156c0120 R08: ffffffff8400fda9 R09: 0000000000000000
R10: 0000000000000005 R11: 0000000080000001 R12: 0000000080000001
R13: ffff88810cd1b280 R14: ffff888029b5f400 R15: ffff8880156c0278
FS:  000000c000030c90(0000) GS:ffff88807dc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffe8ff3fa5f268 CR3: 0000000015c0b000 CR4: 00000000003506f0
----------------
Code disassembly (best guess), 4 bytes skipped:
   0: e9 65 fd ff ff        jmpq   0xfffffd6a
   5: e8 b7 75 3c fd        callq  0xfd3c75c1
   a: 48 c7 c7 26 1c ee 85 mov    $0xffffffff85ee1c26,%rdi
  11: e8 8b fa bc 00        callq  0xbcfaa1
  16: 48 8b 43 30          mov    0x30(%rbx),%rax
  1a: bf 1f 00 00 00        mov    $0x1f,%edi
  1f: 48 8b 80 58 02 00 00 mov    0x258(%rax),%rax
* 26: 65 48 ff 80 40 01 00 incq   %gs:0x140(%rax) <-- trapping instruction
  2d: 00
  2e: 44 0f b6 73 12        movzbl 0x12(%rbx),%r14d
  33: 48 8b 43 30          mov    0x30(%rbx),%rax
  37: 44 89 f6              mov    %r14d,%esi
  3a: 48                    rex.W
  3b: 89                    .byte 0x89

Best,
Wei