syzbot


general protection fault in dup_mmap

Status: moderation: reported on 2025/07/17 06:02
Subsystems: mm
[Documentation on labels]
Reported-by: syzbot+f7bfb8ecb09475450a23@syzkaller.appspotmail.com
First crash: 14d, last: 14d

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xf7fffc000693caa2: 0000 [#1] SMP KASAN PTI
KASAN: maybe wild-memory-access in range [0xc0000000349e5510-0xc0000000349e5517]
CPU: 0 UID: 0 PID: 21548 Comm: syz.0.3792 Not tainted 6.16.0-rc5-next-20250711-syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/07/2025
RIP: 0010:__is_vma_write_locked include/linux/mmap_lock.h:243 [inline]
RIP: 0010:vma_start_write include/linux/mmap_lock.h:264 [inline]
RIP: 0010:dup_mmap+0x548/0x1ac0 mm/mmap.c:1756
Code: 28 84 c0 0f 85 05 0b 00 00 4c 8d 73 10 44 8b 3d ee 8a 94 0d 31 ff 44 89 fe e8 44 5a b0 ff 45 85 ff 74 44 4c 89 f0 48 c1 e8 03 <42> 80 3c 28 00 74 08 4c 89 f7 e8 89 0c 15 00 49 8b 3e b8 e0 01 00
RSP: 0018:ffffc9000db1f820 EFLAGS: 00010a02
RAX: 180000000693caa2 RBX: c0000000349e5500 RCX: 0000000000000000
RDX: ffff888029a5bc00 RSI: 0000000000000001 RDI: 0000000000000000
RBP: ffffc9000db1f9f0 R08: ffff888029a5bc00 R09: 0000000000000004
R10: 0000000000000003 R11: 0000000000000000 R12: ffff88801195d000
R13: dffffc0000000000 R14: c0000000349e5510 R15: 0000000000000001
FS:  00007f02b1f586c0(0000) GS:ffff888125bc6000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbfc16e56c0 CR3: 0000000035706000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 dup_mm kernel/fork.c:1476 [inline]
 copy_mm+0x13c/0x4b0 kernel/fork.c:1528
 copy_process+0x16d3/0x3b80 kernel/fork.c:2165
 kernel_clone+0x21e/0x870 kernel/fork.c:2595
 __do_sys_clone kernel/fork.c:2738 [inline]
 __se_sys_clone kernel/fork.c:2722 [inline]
 __x64_sys_clone+0x18b/0x1e0 kernel/fork.c:2722
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0xfa/0x3b0 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f02b118e929
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f02b1f57fe8 EFLAGS: 00000206 ORIG_RAX: 0000000000000038
RAX: ffffffffffffffda RBX: 00007f02b13b6080 RCX: 00007f02b118e929
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000108200
RBP: 00007f02b1210b39 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000
R13: 0000000000000000 R14: 00007f02b13b6080 R15: 00007ffd6cf8bb48
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
   0:	28 84 c0 0f 85 05 0b 	sub    %al,0xb05850f(%rax,%rax,8)
   7:	00 00                	add    %al,(%rax)
   9:	4c 8d 73 10          	lea    0x10(%rbx),%r14
   d:	44 8b 3d ee 8a 94 0d 	mov    0xd948aee(%rip),%r15d        # 0xd948b02
  14:	31 ff                	xor    %edi,%edi
  16:	44 89 fe             	mov    %r15d,%esi
  19:	e8 44 5a b0 ff       	call   0xffb05a62
  1e:	45 85 ff             	test   %r15d,%r15d
  21:	74 44                	je     0x67
  23:	4c 89 f0             	mov    %r14,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 28 00       	cmpb   $0x0,(%rax,%r13,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	4c 89 f7             	mov    %r14,%rdi
  34:	e8 89 0c 15 00       	call   0x150cc2
  39:	49 8b 3e             	mov    (%r14),%rdi
  3c:	b8                   	.byte 0xb8
  3d:	e0 01                	loopne 0x40

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/07/13 05:57 linux-next a62b7a37e6fc 3cda49cf .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root general protection fault in dup_mmap
* Struck through repros no longer work on HEAD.