syzbot


general protection fault in exfat_find_empty_entry

Status: moderation: reported on 2024/11/29 18:27
Subsystems: exfat
[Documentation on labels]
Reported-by: syzbot+6575ad520e0e2cdcb030@syzkaller.appspotmail.com
First crash: 8d13h, last: 1d02h

Sample crash report:
Oops: general protection fault, probably for non-canonical address 0xdffffc0000000003: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000018-0x000000000000001f]
CPU: 0 UID: 0 PID: 5315 Comm: syz.0.0 Not tainted 6.13.0-rc1-syzkaller-00002-gcdd30ebb1b9f #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2~bpo12+1 04/01/2014
RIP: 0010:exfat_find_empty_entry+0x16c9/0x1a10 fs/exfat/namei.c:398
Code: 7a 89 ff 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 05 7a 89 ff 48 8b 1b 48 83 c3 18 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 e8 79 89 ff 4c 8b 33 48 8b 54 24
RSP: 0018:ffffc9000d447120 EFLAGS: 00010206
RAX: 0000000000000003 RBX: 0000000000000018 RCX: ffff888000ed4880
RDX: 0000000000000000 RSI: 00000000fffffffb RDI: 00000000fffffffb
RBP: ffffc9000d447370 R08: ffffffff8280d378 R09: 1ffff1100a48fe9d
R10: dffffc0000000000 R11: ffffed100a48fe9e R12: 00000000fffffffb
R13: ffffc9000d447820 R14: ffff8880524d01a8 R15: dffffc0000000000
FS:  00007fa13c3c36c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdbc0eff40 CR3: 0000000043116000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 exfat_add_entry+0x409/0xaa0 fs/exfat/namei.c:496
 exfat_create+0x1c7/0x570 fs/exfat/namei.c:565
 lookup_open fs/namei.c:3649 [inline]
 open_last_lookups fs/namei.c:3748 [inline]
 path_openat+0x1c03/0x3590 fs/namei.c:3984
 do_filp_open+0x27f/0x4e0 fs/namei.c:4014
 do_sys_openat2+0x13e/0x1d0 fs/open.c:1402
 do_sys_open fs/open.c:1417 [inline]
 __do_sys_openat fs/open.c:1433 [inline]
 __se_sys_openat fs/open.c:1428 [inline]
 __x64_sys_openat+0x247/0x2a0 fs/open.c:1428
 do_syscall_x64 arch/x86/entry/common.c:52 [inline]
 do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fa13b57ff19
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:00007fa13c3c3058 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 00007fa13b746160 RCX: 00007fa13b57ff19
RDX: 000000000000275a RSI: 00000000200000c0 RDI: ffffffffffffff9c
RBP: 00007fa13b5f3986 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000001 R14: 00007fa13b746160 R15: 00007ffdbc0f08f8
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:exfat_find_empty_entry+0x16c9/0x1a10 fs/exfat/namei.c:398
Code: 7a 89 ff 48 8b 1b 48 89 d8 48 c1 e8 03 42 80 3c 38 00 74 08 48 89 df e8 05 7a 89 ff 48 8b 1b 48 83 c3 18 48 89 d8 48 c1 e8 03 <42> 80 3c 38 00 74 08 48 89 df e8 e8 79 89 ff 4c 8b 33 48 8b 54 24
RSP: 0018:ffffc9000d447120 EFLAGS: 00010206
RAX: 0000000000000003 RBX: 0000000000000018 RCX: ffff888000ed4880
RDX: 0000000000000000 RSI: 00000000fffffffb RDI: 00000000fffffffb
RBP: ffffc9000d447370 R08: ffffffff8280d378 R09: 1ffff1100a48fe9d
R10: dffffc0000000000 R11: ffffed100a48fe9e R12: 00000000fffffffb
R13: ffffc9000d447820 R14: ffff8880524d01a8 R15: dffffc0000000000
FS:  00007fa13c3c36c0(0000) GS:ffff88801fc00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffdbc0eff40 CR3: 0000000043116000 CR4: 0000000000352ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	7a 89                	jp     0xffffff8b
   2:	ff 48 8b             	decl   -0x75(%rax)
   5:	1b 48 89             	sbb    -0x77(%rax),%ecx
   8:	d8 48 c1             	fmuls  -0x3f(%rax)
   b:	e8 03 42 80 3c       	call   0x3c804213
  10:	38 00                	cmp    %al,(%rax)
  12:	74 08                	je     0x1c
  14:	48 89 df             	mov    %rbx,%rdi
  17:	e8 05 7a 89 ff       	call   0xff897a21
  1c:	48 8b 1b             	mov    (%rbx),%rbx
  1f:	48 83 c3 18          	add    $0x18,%rbx
  23:	48 89 d8             	mov    %rbx,%rax
  26:	48 c1 e8 03          	shr    $0x3,%rax
* 2a:	42 80 3c 38 00       	cmpb   $0x0,(%rax,%r15,1) <-- trapping instruction
  2f:	74 08                	je     0x39
  31:	48 89 df             	mov    %rbx,%rdi
  34:	e8 e8 79 89 ff       	call   0xff897a21
  39:	4c 8b 33             	mov    (%rbx),%r14
  3c:	48                   	rex.W
  3d:	8b                   	.byte 0x8b
  3e:	54                   	push   %rsp
  3f:	24                   	.byte 0x24

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/12/03 05:10 upstream cdd30ebb1b9f bb326ffb .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root general protection fault in exfat_find_empty_entry
2024/11/25 18:25 linux-next 85a2dd7d7c81 a84878fc .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-linux-next-kasan-gce-root general protection fault in exfat_find_empty_entry
* Struck through repros no longer work on HEAD.