general protection fault in vsscanf

Status: upstream: reported C repro on 2026/08/18 22:35
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+b68e1136e003bd0a4101@syzkaller.appspotmail.com
First crash: 4d06h, last: 3d15h
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2026/08/19 linux-5.15.y (ToT) aabd761612db C [report] general protection fault in vsscanf
2026/08/19 upstream (ToT) bd5f485f3f02 C Didn't crash
▶ ▼ Similar bugs (11)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-6-1 general protection fault in vsscanf 2 syz, C 20 41m 4d18h 0/2 upstream: reported C repro on 2026/08/18 10:26
linux-6.6 general protection fault in vsscanf 2 syz, C 7 3d18h 3d20h 0/2 upstream: reported C repro on 2026/08/19 08:56
android-5-15 general protection fault in vsscanf 2 syz, C 7 1d20h 4d07h 0/2 upstream: reported C repro on 2026/08/18 22:10
upstream general protection fault in vsscanf (2) mm 2 syz, C 11 609d 615d 28/29 fixed on 2025/05/06 15:33
upstream general protection fault in vsscanf v9fs 2 syz, C 7 2935d 2965d 8/29 fixed on 2018/09/03 14:47
android-49 general protection fault in vsscanf 2 syz, C 6 2915d 2688d 0/3 public: reported C repro on 2019/04/14 00:00
android-6-12 general protection fault in vsscanf 2 syz, C 9 3d17h 5d01h 0/1 premoderation: reported C repro on 2026/08/18 03:15
linux-6.1 BUG: unable to handle kernel paging request in vsscanf 8 syz, C 9 4d04h 4d13h 0/3 upstream: reported C repro on 2026/08/18 15:35
linux-4.19 BUG: unable to handle kernel paging request in vsscanf (2) 8 2 1773d 1875d 0/1 auto-closed as invalid on 2022/02/11 22:53
upstream KMSAN: uninit-value in vsscanf bluetooth 7 syz 9 1634d 1700d 0/29 auto-closed as invalid on 2022/09/27 18:52
linux-4.19 BUG: unable to handle kernel paging request in vsscanf (3) 8 1 1581d 1581d 0/1 auto-closed as invalid on 2022/08/22 19:56

Sample crash report:
general protection fault, probably for non-canonical address 0xdffffc0000000000: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000000-0x0000000000000007]
CPU: 0 PID: 4487 Comm: syz.0.17 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026
RIP: 0010:vsscanf+0x196/0x24b0 lib/vsprintf.c:3450
Code: 48 c7 c6 e0 fb 94 8c e8 c8 ff 6c fd 41 83 fe 25 74 4d 45 85 f6 0f 84 b6 21 00 00 48 ff c3 48 89 5c 24 78 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4f 1b 00 00 41 0f b6 1f 45 0f b6 f6 44
RSP: 0018:ffffc9000321f600 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff8a35bae1 RCX: 0000000000000001
RDX: ffffffff840c0148 RSI: ffffffff8c94fbe0 RDI: 0000000000000030
RBP: ffffc9000321f730 R08: ffff8880215dbb80 R09: 0000000000000002
R10: 0000000000000025 R11: 0000000000000000 R12: ffffffff8a35bae0
R13: dffffc0000000000 R14: 0000000000000030 R15: 0000000000000000
FS:  000055555c9c7500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b2da63fff CR3: 0000000022ad1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 sscanf+0xdf/0x130 lib/vsprintf.c:3708
 split_huge_pages_write+0x30d/0x1750 mm/huge_memory.c:3112
 full_proxy_write+0x109/0x1c0 fs/debugfs/file.c:244
 vfs_write+0x304/0xd70 fs/read_write.c:592
 ksys_write+0x153/0x260 fs/read_write.c:647
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x66/0xd0
RIP: 0033:0x7f62ce9f90d9
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:00007ffe514ae0f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000001
RAX: ffffffffffffffda RBX: 00007f62cec80fa0 RCX: 00007f62ce9f90d9
RDX: 0000000000000005 RSI: 0000200000000600 RDI: 0000000000000003
RBP: 00007f62cea90024 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f62cec80fac R14: 00007f62cec80fa0 R15: 00007f62cec80fa0
 </TASK>
Modules linked in:
---[ end trace 9730491ac5643c78 ]---
RIP: 0010:vsscanf+0x196/0x24b0 lib/vsprintf.c:3450
Code: 48 c7 c6 e0 fb 94 8c e8 c8 ff 6c fd 41 83 fe 25 74 4d 45 85 f6 0f 84 b6 21 00 00 48 ff c3 48 89 5c 24 78 4c 89 f8 48 c1 e8 03 <42> 0f b6 04 28 84 c0 0f 85 4f 1b 00 00 41 0f b6 1f 45 0f b6 f6 44
RSP: 0018:ffffc9000321f600 EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffffffff8a35bae1 RCX: 0000000000000001
RDX: ffffffff840c0148 RSI: ffffffff8c94fbe0 RDI: 0000000000000030
RBP: ffffc9000321f730 R08: ffff8880215dbb80 R09: 0000000000000002
R10: 0000000000000025 R11: 0000000000000000 R12: ffffffff8a35bae0
R13: dffffc0000000000 R14: 0000000000000030 R15: 0000000000000000
FS:  000055555c9c7500(0000) GS:ffff8880b9000000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005568b63a2950 CR3: 0000000022ad1000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	48 c7 c6 e0 fb 94 8c 	mov    $0xffffffff8c94fbe0,%rsi
   7:	e8 c8 ff 6c fd       	call   0xfd6cffd4
   c:	41 83 fe 25          	cmp    $0x25,%r14d
  10:	74 4d                	je     0x5f
  12:	45 85 f6             	test   %r14d,%r14d
  15:	0f 84 b6 21 00 00    	je     0x21d1
  1b:	48 ff c3             	inc    %rbx
  1e:	48 89 5c 24 78       	mov    %rbx,0x78(%rsp)
  23:	4c 89 f8             	mov    %r15,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 0f b6 04 28       	movzbl (%rax,%r13,1),%eax <-- trapping instruction
  2f:	84 c0                	test   %al,%al
  31:	0f 85 4f 1b 00 00    	jne    0x1b86
  37:	41 0f b6 1f          	movzbl (%r15),%ebx
  3b:	45 0f b6 f6          	movzbl %r14b,%r14d
  3f:	44                   	rex.R

Crashes (6):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/08/18 23:35 linux-5.15.y aabd761612db 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
2026/08/18 23:04 linux-5.15.y aabd761612db 1e72964b .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
2026/08/19 01:12 linux-5.15.y aabd761612db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
2026/08/19 01:11 linux-5.15.y aabd761612db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
2026/08/18 22:34 linux-5.15.y aabd761612db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
2026/08/18 22:34 linux-5.15.y aabd761612db 1e72964b .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan general protection fault in vsscanf
* Struck through repros no longer work on HEAD.