[moderation] [block?] BUG: unable to handle kernel NULL pointer dereference in const_folio_flags

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 96e09b8f8166 Merge tag 'platform-drivers-x86-v6.10-3' of g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14221932980000
kernel config: https://syzkaller.appspot.com/x/.config?x=96fd46a1ee1615e0
dashboard link: https://syzkaller.appspot.com/bug?extid=00b95c1af2f8ca2cb660
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
userspace arch: i386
CC: [ax...@kernel.dk linux...@vger.kernel.org linux-...@vger.kernel.org]

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/7bc7510fe41f/non_bootable_disk-96e09b8f.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d2bf80e54d1f/vmlinux-96e09b8f.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b81837ec8c21/bzImage-96e09b8f.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+00b95c...@syzkaller.appspotmail.com

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)


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