syzbot


BUG: unable to handle kernel NULL pointer dereference in const_folio_flags

Status: moderation: reported on 2024/06/12 10:35
Subsystems: block
[Documentation on labels]
Reported-by: syzbot+00b95c1af2f8ca2cb660@syzkaller.appspotmail.com
First crash: 40d, last: 40d

Sample crash report:
BUG: kernel NULL pointer dereference, address: 000000000000000c
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 7c4067 P4D 7c4067 PUD 62173067 PMD 0 
Oops: Oops: 0000 [#1] PREEMPT SMP KASAN NOPTI
CPU: 2 PID: 10845 Comm: syz-executor.0 Not tainted 6.10.0-rc2-syzkaller-00269-g96e09b8f8166 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:PageTail include/linux/page-flags.h:284 [inline]
RIP: 0010:const_folio_flags.constprop.0+0x0/0x50 include/linux/page-flags.h:312
Code: a1 24 8d e8 a2 24 f1 ff 90 0f 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <48> 8b 47 08 a8 01 75 2a 66 90 48 89 f8 c3 cc cc cc cc f7 c7 ff 0f
RSP: 0018:ffffc90002f671f8 EFLAGS: 00010246
RAX: ffffffff81e19f28 RBX: ffffe8ffad26e820 RCX: ffffffff81c2f68e
RDX: 00000000ffffffff RSI: 0000000000000cc0 RDI: 0000000000000004
RBP: ffffc90002f672e0 R08: ffffe8ffad26e820 R09: 00000000000004a8
R10: ffffc90002f67300 R11: 0000000000000001 R12: ffffe8ffad26e820
R13: ffff88805a6e8c80 R14: 0000000000000004 R15: 00000000ffffffff
FS:  0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5ed2b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000000000000c CR3: 0000000000a86000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 folio_test_active include/linux/page-flags.h:522 [inline]
 slab_test_pfmemalloc mm/slab.h:169 [inline]
 pfmemalloc_match mm/slub.c:3398 [inline]
 ___slab_alloc+0x3d4/0x1870 mm/slub.c:3539
 __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
 mempool_init_node+0x31e/0x760 mm/mempool.c:217
 mempool_init_noprof+0x3a/0x50 mm/mempool.c:246
 bioset_init+0x324/0x7a0 block/bio.c:1785
 bch2_fs_fs_io_direct_init+0x58/0x90 fs/bcachefs/fs-io-direct.c:681
 bch2_fs_alloc+0x1abb/0x2550 fs/bcachefs/super.c:926
 bch2_fs_open+0x713/0x10f0 fs/bcachefs/super.c:2102
 bch2_mount+0xdc9/0x1140 fs/bcachefs/fs.c:1917
 legacy_get_tree+0x109/0x220 fs/fs_context.c:662
 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: 0023:0xf72e0579
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:00000000f5ed2400 EFLAGS: 00000292 ORIG_RAX: 0000000000000015
RAX: ffffffffffffffda RBX: 00000000f5ed2460 RCX: 0000000020000700
RDX: 0000000020000000 RSI: 0000000000000000 RDI: 00000000f5ed24a0
RBP: 00000000f5ed2460 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000296 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
CR2: 000000000000000c
---[ end trace 0000000000000000 ]---
RIP: 0010:PageTail include/linux/page-flags.h:284 [inline]
RIP: 0010:const_folio_flags.constprop.0+0x0/0x50 include/linux/page-flags.h:312
Code: a1 24 8d e8 a2 24 f1 ff 90 0f 0b 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 <48> 8b 47 08 a8 01 75 2a 66 90 48 89 f8 c3 cc cc cc cc f7 c7 ff 0f
RSP: 0018:ffffc90002f671f8 EFLAGS: 00010246
RAX: ffffffff81e19f28 RBX: ffffe8ffad26e820 RCX: ffffffff81c2f68e
RDX: 00000000ffffffff RSI: 0000000000000cc0 RDI: 0000000000000004
RBP: ffffc90002f672e0 R08: ffffe8ffad26e820 R09: 00000000000004a8
R10: ffffc90002f67300 R11: 0000000000000001 R12: ffffe8ffad26e820
R13: ffff88805a6e8c80 R14: 0000000000000004 R15: 00000000ffffffff
FS:  0000000000000000(0000) GS:ffff88802c200000(0063) knlGS:00000000f5ed2b40
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 000000000000000c CR3: 0000000000a86000 CR4: 0000000000350ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
   0:	a1 24 8d e8 a2 24 f1 	movabs 0x90fff124a2e88d24,%eax
   7:	ff 90
   9:	0f 0b                	ud2
   b:	66 66 2e 0f 1f 84 00 	data16 cs nopw 0x0(%rax,%rax,1)
  12:	00 00 00 00
  16:	0f 1f 40 00          	nopl   0x0(%rax)
  1a:	90                   	nop
  1b:	90                   	nop
  1c:	90                   	nop
  1d:	90                   	nop
  1e:	90                   	nop
  1f:	90                   	nop
  20:	90                   	nop
  21:	90                   	nop
  22:	90                   	nop
  23:	90                   	nop
  24:	90                   	nop
  25:	90                   	nop
  26:	90                   	nop
  27:	90                   	nop
  28:	90                   	nop
  29:	90                   	nop
* 2a:	48 8b 47 08          	mov    0x8(%rdi),%rax <-- trapping instruction
  2e:	a8 01                	test   $0x1,%al
  30:	75 2a                	jne    0x5c
  32:	66 90                	xchg   %ax,%ax
  34:	48 89 f8             	mov    %rdi,%rax
  37:	c3                   	ret
  38:	cc                   	int3
  39:	cc                   	int3
  3a:	cc                   	int3
  3b:	cc                   	int3
  3c:	f7                   	.byte 0xf7
  3d:	c7                   	(bad)
  3e:	ff 0f                	decl   (%rdi)

Crashes (1):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2024/06/08 10:24 upstream 96e09b8f8166 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 const_folio_flags
* Struck through repros no longer work on HEAD.