Hello.
We are Ubisectech Sirius Team, the vulnerability lab of China ValiantSec. Recently, our team has discovered a issue in Linux kernel 6.7. Attached to the email were a PoC file of the issue.
Stack dump:
general protection fault, probably for non-canonical address 0xdffffc0000000002: 0000 [#1] PREEMPT SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000010-0x0000000000000017]
CPU: 0 PID: 10008 Comm: syz-executor.3 Not tainted 6.7.0 #2
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 04/01/2014
RIP: 0010:bch2_snapshot_is_internal_node fs/bcachefs/snapshot.h:143 [inline]
RIP: 0010:btree_insert_entry_checks fs/bcachefs/btree_trans_commit.c:318 [inline]
RIP: 0010:__bch2_trans_commit+0x1630/0x6d60 fs/bcachefs/btree_trans_commit.c:1060
Code: 26 5b c7 fd 8b 85 e8 fe ff ff 85 c0 0f 85 2d 3b 00 00 e8 73 5f c7 fd 41 f7 d4 49 6b c4 38 49 8d 7c 06 14 48 89 f8 48 c1 e8 03 <0f> b6 14 18 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 ea
RSP: 0018:ffffc90002437378 EFLAGS: 00010203
RAX: 0000000000000002 RBX: dffffc0000000000 RCX: ffffc90005fa2000
RDX: 0000000000040000 RSI: ffffffff83c296dd RDI: 0000000000000014
RBP: ffffc90002437550 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff83c29668 R12: 0000000000000000
R13: ffff88804c65a558 R14: 0000000000000000 R15: ffff88804c65a560
FS: 00007ffb04b55640(0000) GS:ffff88802c600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f48f35daf88 CR3: 000000005ca2c000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
<TASK>
bch2_trans_commit fs/bcachefs/btree_update.h:137 [inline]
__bch2_create+0x857/0xeb0 fs/bcachefs/fs.c:280
bch2_mknod fs/bcachefs/fs.c:379 [inline]
bch2_create+0x41/0xc0 fs/bcachefs/fs.c:393
lookup_open.isra.0+0xfc9/0x1370 fs/namei.c:3477
open_last_lookups fs/namei.c:3546 [inline]
path_openat+0xa89/0x26d0 fs/namei.c:3776
do_filp_open+0x1c9/0x420 fs/namei.c:3809
do_sys_openat2+0x164/0x1d0 fs/open.c:1437
do_sys_open fs/open.c:1452 [inline]
__do_sys_creat fs/open.c:1528 [inline]
__se_sys_creat fs/open.c:1522 [inline]
__x64_sys_creat+0xcd/0x120 fs/open.c:1522
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x43/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x6f/0x77
RIP: 0033:0x7ffb03e8fd6d
Code: c3 e8 97 2b 00 00 0f 1f 80 00 00 00 00 f3 0f 1e fa 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffb04b55028 EFLAGS: 00000246 ORIG_RAX: 0000000000000055
RAX: ffffffffffffffda RBX: 00007ffb03fcbf80 RCX: 00007ffb03e8fd6d
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000020000480
RBP: 00007ffb03ef14cd R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 000000000000000b R14: 00007ffb03fcbf80 R15: 00007ffb04b35000
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bch2_snapshot_is_internal_node fs/bcachefs/snapshot.h:143 [inline]
RIP: 0010:btree_insert_entry_checks fs/bcachefs/btree_trans_commit.c:318 [inline]
RIP: 0010:__bch2_trans_commit+0x1630/0x6d60 fs/bcachefs/btree_trans_commit.c:1060
Code: 26 5b c7 fd 8b 85 e8 fe ff ff 85 c0 0f 85 2d 3b 00 00 e8 73 5f c7 fd 41 f7 d4 49 6b c4 38 49 8d 7c 06 14 48 89 f8 48 c1 e8 03 <0f> b6 14 18 48 89 f8 83 e0 07 83 c0 03 38 d0 7c 08 84 d2 0f 85 ea
RSP: 0018:ffffc90002437378 EFLAGS: 00010203
RAX: 0000000000000002 RBX: dffffc0000000000 RCX: ffffc90005fa2000
RDX: 0000000000040000 RSI: ffffffff83c296dd RDI: 0000000000000014
RBP: ffffc90002437550 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000001 R11: ffffffff83c29668 R12: 0000000000000000
R13: ffff88804c65a558 R14: 0000000000000000 R15: ffff88804c65a560
FS: 00007ffb04b55640(0000) GS:ffff88802c600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f48f34f56c6 CR3: 000000005ca2c000 CR4: 0000000000750ef0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
----------------
Code disassembly (best guess), 3 bytes skipped:
0: fd std
1: 8b 85 e8 fe ff ff mov -0x118(%rbp),%eax
7: 85 c0 test %eax,%eax
9: 0f 85 2d 3b 00 00 jne 0x3b3c
f: e8 73 5f c7 fd call 0xfdc75f87
14: 41 f7 d4 not %r12d
17: 49 6b c4 38 imul $0x38,%r12,%rax
1b: 49 8d 7c 06 14 lea 0x14(%r14,%rax,1),%rdi
20: 48 89 f8 mov %rdi,%rax
23: 48 c1 e8 03 shr $0x3,%rax
* 27: 0f b6 14 18 movzbl (%rax,%rbx,1),%edx <-- trapping instruction
2b: 48 89 f8 mov %rdi,%rax
2e: 83 e0 07 and $0x7,%eax
31: 83 c0 03 add $0x3,%eax
34: 38 d0 cmp %dl,%al
36: 7c 08 jl 0x40
38: 84 d2 test %dl,%dl
3a: 0f .byte 0xf
3b: 85 ea test %ebp,%edx
Thank you for taking the time to read this email and we look forward to working with you further.