general protection fault in cdev_del

Status: premoderation: reported on 2026/10/25 20:16
Reported-by: syzbot+e07c0adfb01fed6f3b1b@syzkaller.appspotmail.com
First crash: 5d23h, last: 5d23h
▶ ▼ Similar bugs (4)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
upstream general protection fault in cdev_del (2) fs 11 syz, C error 45 1950d 2228d 20/29 fixed on 2021/11/10 00:50
upstream general protection fault in cdev_del usb fs 2 syz, C 315 2245d 2713d 15/29 fixed on 2020/09/16 22:51
linux-4.19 general protection fault in cdev_del vfs 2 syz, C 415 1335d 2518d 0/1 upstream: reported C repro on 2019/12/09 03:59
linux-4.14 general protection fault in cdev_del vfs 2 syz, C 279 1336d 2523d 0/1 upstream: reported C repro on 2019/12/04 03:14

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000010: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000080-0x0000000000000087]
CPU: 1 PID: 12210 Comm: syz.0.3476 Tainted: G    B   W         syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/07/2026
RIP: 0010:cdev_del+0x27/0xa0 fs/char_dev.c:596
Code: eb aa 90 55 48 89 e5 41 56 53 48 89 fb 49 be 00 00 00 00 00 fc ff df e8 e7 b9 bc ff 48 8d bb 80 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 3c 8b b3 80 00 00 00 48 8d bb 84 00 00 00
RSP: 0018:ffffc90000e37880 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000b722000 RSI: 00000000000003bd RDI: 0000000000000080
RBP: ffffc90000e37890 R08: ffff888100bed8a3 R09: 1ffff1102017db14
R10: dffffc0000000000 R11: ffffed102017db15 R12: dffffc0000000000
R13: 1ffff110204f4181 R14: dffffc0000000000 R15: ffff888100becc00
FS:  00007f73d3c3e6c0(0000) GS:ffff8881f7100000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b30418ff8 CR3: 000000011c595000 CR4: 00000000003506a0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 tty_unregister_device+0xe6/0x180 drivers/tty/tty_io.c:3292
 tty_port_unregister_device+0x3e/0x50 drivers/tty/tty_port.c:211
 uart_remove_one_port+0x1ce/0x780 drivers/tty/serial/serial_core.c:3084
 serial8250_unregister_port+0xad/0x260 drivers/tty/serial/8250/8250_core.c:1156
 serial_pnp_remove+0x6b/0x90 drivers/tty/serial/8250/8250_pnp.c:498
 pnp_device_remove+0x75/0x250 drivers/pnp/driver.c:131
 __device_release_driver drivers/base/dd.c:-1 [inline]
 device_release_driver_internal+0x531/0x7c0 drivers/base/dd.c:1221
 device_driver_detach+0x3b/0x40 drivers/base/dd.c:1257
 unbind_store+0x2e5/0x300 drivers/base/bus.c:193
 drv_attr_store+0x79/0xa0 drivers/base/bus.c:77
 sysfs_kf_write+0x129/0x150 fs/sysfs/file.c:143
 kernfs_fop_write_iter+0x2bd/0x400 fs/kernfs/file.c:296
 call_write_iter include/linux/fs.h:2072 [inline]
 new_sync_write fs/read_write.c:518 [inline]
 vfs_write+0x770/0xd70 fs/read_write.c:605
 ksys_write+0x14a/0x260 fs/read_write.c:658
 __do_sys_write fs/read_write.c:670 [inline]
 __se_sys_write fs/read_write.c:667 [inline]
 __x64_sys_write+0x7b/0x90 fs/read_write.c:667
 do_syscall_64+0x31/0x40 arch/x86/entry/common.c:46
 entry_SYSCALL_64_after_hwframe+0x61/0xcb
RIP: 0033:0x7f73d51e6559
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f73d3c3e028 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f73d546cfa0 RCX: 00007f73d51e6559
RDX: 0000000000000005 RSI: 0000200000000880 RDI: 0000000000000005
RBP: 00007f73d527db20 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f73d546d038 R14: 00007f73d546cfa0 R15: 00007fff97694c78
Modules linked in:
---[ end trace 91fd082670bf2473 ]---
RIP: 0010:cdev_del+0x27/0xa0 fs/char_dev.c:596
Code: eb aa 90 55 48 89 e5 41 56 53 48 89 fb 49 be 00 00 00 00 00 fc ff df e8 e7 b9 bc ff 48 8d bb 80 00 00 00 48 89 f8 48 c1 e8 03 <42> 0f b6 04 30 84 c0 75 3c 8b b3 80 00 00 00 48 8d bb 84 00 00 00
RSP: 0018:ffffc90000e37880 EFLAGS: 00010202
RAX: 0000000000000010 RBX: 0000000000000000 RCX: 0000000000080000
RDX: ffffc9000b722000 RSI: 00000000000003bd RDI: 0000000000000080
RBP: ffffc90000e37890 R08: ffff888100bed8a3 R09: 1ffff1102017db14
R10: dffffc0000000000 R11: ffffed102017db15 R12: dffffc0000000000
R13: 1ffff110204f4181 R14: dffffc0000000000 R15: ffff888100becc00
FS:  00007f73d3c3e6c0(0000) GS:ffff8881f7000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f07db0732f8 CR3: 000000011c595000 CR4: 00000000003506b0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	eb aa                	jmp    0xffffffac
   2:	90                   	nop
   3:	55                   	push   %rbp
   4:	48 89 e5             	mov    %rsp,%rbp
   7:	41 56                	push   %r14
   9:	53                   	push   %rbx
   a:	48 89 fb             	mov    %rdi,%rbx
   d:	49 be 00 00 00 00 00 	movabs $0xdffffc0000000000,%r14
  14:	fc ff df
  17:	e8 e7 b9 bc ff       	call   0xffbcba03
  1c:	48 8d bb 80 00 00 00 	lea    0x80(%rbx),%rdi
  23:	48 89 f8             	mov    %rdi,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 30       	movzbl (%rax,%r14,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	75 3c                	jne    0x6f
  33:	8b b3 80 00 00 00    	mov    0x80(%rbx),%esi
  39:	48 8d bb 84 00 00 00 	lea    0x84(%rbx),%rdi

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/10/25 20:15 android13-5.10-lts f61a392235e0 1d9ca40b .config console log report info [disk image] [vmlinux] [kernel image] ci2-android-5-10 general protection fault in cdev_del
* Struck through repros no longer work on HEAD.