syzbot


BUG: unable to handle kernel NULL pointer dereference in ext4_mb_add_groupinfo

Status: moderation: reported on 2024/06/10 00:55
Subsystems: ext4
[Documentation on labels]
Reported-by: syzbot+5628dd935014d960de7f@syzkaller.appspotmail.com
First crash: 9d16h, last: 9d16h

Sample crash report:
loop2: detected capacity change from 0 to 512
EXT4-fs (loop2): revision level too high, forcing read-only mode
[EXT4 FS bs=1024, gc=1, bpg=8192, ipg=32, mo=8842c01c, mo2=0002]
BUG: kernel NULL pointer dereference, address: 0000000000000011
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 58544067 P4D 58544067 PUD 61d96067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 2 PID: 8653 Comm: syz-executor.2 Not tainted 6.10.0-rc2-syzkaller-00064-g71d7b52cc33b #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:___slab_alloc+0x27a/0x1870 mm/slub.c:3609
Code: 0b 49 83 7f 28 00 0f 85 de 07 00 00 4d 89 77 28 49 83 7c 24 10 00 0f 85 45 06 00 00 4d 8b 7c 24 18 4d 85 ff 0f 84 d2 06 00 00 <49> 8b 47 10 83 bd 68 ff ff ff ff 49 89 44 24 18 74 20 49 8b 07 48
RSP: 0018:ffffc90004fbf820 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000202 RCX: ffffffff816bc84e
RDX: 0000000000000001 RSI: ffffffff81e1a018 RDI: 0000000000000000
RBP: ffffc90004fbf900 R08: 0000000000000000 R09: fffffbfff283f058
R10: ffffffff941f82c7 R11: 0000000000000001 R12: ffffe8ffad26aba0
R13: ffff888019157680 R14: ffff88801bfd0000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5f30b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000011 CR3: 00000000632a8000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 __slab_alloc.constprop.0+0x56/0xb0 mm/slub.c:3756
 __slab_alloc_node mm/slub.c:3809 [inline]
 slab_alloc_node mm/slub.c:3988 [inline]
 kmem_cache_alloc_noprof+0x2ae/0x2f0 mm/slub.c:4007
 ext4_mb_add_groupinfo+0x445/0x1180 fs/ext4/mballoc.c:3355
 ext4_mb_init_backend fs/ext4/mballoc.c:3434 [inline]
 ext4_mb_init+0x127a/0x2530 fs/ext4/mballoc.c:3732
 __ext4_fill_super fs/ext4/super.c:5501 [inline]
 ext4_fill_super+0x6d55/0xacf0 fs/ext4/super.c:5676
 get_tree_bdev+0x36f/0x610 fs/super.c:1615
 vfs_get_tree+0x8f/0x380 fs/super.c:1780
 do_new_mount fs/namespace.c:3352 [inline]
 path_mount+0x6e1/0x1f10 fs/namespace.c:3679
 do_mount fs/namespace.c:3692 [inline]
 __do_sys_mount fs/namespace.c:3898 [inline]
 __se_sys_mount fs/namespace.c:3875 [inline]
 __ia32_sys_mount+0x295/0x320 fs/namespace.c:3875
 do_syscall_32_irqs_on arch/x86/entry/common.c:165 [inline]
 __do_fast_syscall_32+0x73/0x120 arch/x86/entry/common.c:386
 do_fast_syscall_32+0x32/0x80 arch/x86/entry/common.c:411
 entry_SYSENTER_compat_after_hwframe+0x84/0x8e
RIP: 0023:0xf733e579
Code: b8 01 10 06 03 74 b4 01 10 07 03 74 b0 01 10 08 03 74 d8 01 00 00 00 00 00 00 00 00 00 00 00 00 00 51 52 55 89 e5 0f 34 cd 80 <5d> 5a 59 c3 90 90 90 90 8d b4 26 00 00 00 00 8d b4 26 00 00 00 00
RSP: 002b:00000000f5f30400 EFLAGS: 00000292 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00000000f5f30460 RCX: 0000000020000380
RDX: 0000000020000040 RSI: 0000000022000011 RDI: 00000000f5f304a0
RBP: 00000000f5f30460 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: 0000000000000011
---[ end trace 0000000000000000 ]---
RIP: 0010:___slab_alloc+0x27a/0x1870 mm/slub.c:3609
Code: 0b 49 83 7f 28 00 0f 85 de 07 00 00 4d 89 77 28 49 83 7c 24 10 00 0f 85 45 06 00 00 4d 8b 7c 24 18 4d 85 ff 0f 84 d2 06 00 00 <49> 8b 47 10 83 bd 68 ff ff ff ff 49 89 44 24 18 74 20 49 8b 07 48
RSP: 0018:ffffc90004fbf820 EFLAGS: 00010002
RAX: 0000000000000000 RBX: 0000000000000202 RCX: ffffffff816bc84e
RDX: 0000000000000001 RSI: ffffffff81e1a018 RDI: 0000000000000000
RBP: ffffc90004fbf900 R08: 0000000000000000 R09: fffffbfff283f058
R10: ffffffff941f82c7 R11: 0000000000000001 R12: ffffe8ffad26aba0
R13: ffff888019157680 R14: ffff88801bfd0000 R15: 0000000000000001
FS:  0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5f30b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 0000000000000011 CR3: 00000000632a8000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
   0:	49 83 7f 28 00       	cmpq   $0x0,0x28(%r15)
   5:	0f 85 de 07 00 00    	jne    0x7e9
   b:	4d 89 77 28          	mov    %r14,0x28(%r15)
   f:	49 83 7c 24 10 00    	cmpq   $0x0,0x10(%r12)
  15:	0f 85 45 06 00 00    	jne    0x660
  1b:	4d 8b 7c 24 18       	mov    0x18(%r12),%r15
  20:	4d 85 ff             	test   %r15,%r15
  23:	0f 84 d2 06 00 00    	je     0x6fb
* 29:	49 8b 47 10          	mov    0x10(%r15),%rax <-- trapping instruction
  2d:	83 bd 68 ff ff ff ff 	cmpl   $0xffffffff,-0x98(%rbp)
  34:	49 89 44 24 18       	mov    %rax,0x18(%r12)
  39:	74 20                	je     0x5b
  3b:	49 8b 07             	mov    (%r15),%rax
  3e:	48                   	rex.W

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/06 00:46 upstream 71d7b52cc33b c2e07261 .config console log report info [disk image (non-bootable)] [vmlinux] [kernel image] ci-qemu-upstream-386 BUG: unable to handle kernel NULL pointer dereference in ext4_mb_add_groupinfo
* Struck through repros no longer work on HEAD.