[syzbot] [kernfs?] general protection fault in simple_xattrs_free

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: c9b47175e913 Merge tag 'i2c-for-6.19-rc1' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=15d6b992580000
kernel config: https://syzkaller.appspot.com/x/.config?x=73d2ed7b46aaccf3
dashboard link: https://syzkaller.appspot.com/bug?extid=6aaf7f48ae034ab0ea97
compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2734f5f5b7ce/disk-c9b47175.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/1c3a22149cb4/vmlinux-c9b47175.xz
kernel image: https://storage.googleapis.com/syzbot-assets/31b27436ea99/bzImage-c9b47175.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+6aaf7f...@syzkaller.appspotmail.com

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000007: 0000 [#1] SMP KASAN NOPTI
KASAN: null-ptr-deref in range [0x0000000000000038-0x000000000000003f]
CPU: 0 UID: 0 PID: 6570 Comm: syz.0.148 Tainted: G L syzkaller #0 PREEMPT(full)
Tainted: [L]=SOFTLOCKUP
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/25/2025
RIP: 0010:rb_first include/linux/rbtree.h:54 [inline]
RIP: 0010:simple_xattrs_free+0x60/0x1e0 fs/xattr.c:1564
Code: ea 03 80 3c 02 00 0f 85 8b 01 00 00 49 c7 45 00 00 00 00 00 e8 e1 a5 75 ff 4c 89 fa 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 56 01 00 00 48 bd 00 00 00 00 00 fc ff df 49 8b
RSP: 0018:ffffc9000f70fae0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88807c948f00 RCX: ffffc9000d3d9000
RDX: 0000000000000007 RSI: ffffffff82493e8f RDI: 0000000000000038
RBP: ffff88807c948f98 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffffea R11: ffffffff82287bd4 R12: 1ffff92001ee1f6b
R13: 0000000000000000 R14: ffff88814d735560 R15: 0000000000000038
FS: 00007f999b1626c0(0000) GS:ffff8881248fd000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000110c3aa75e CR3: 0000000021fa5000 CR4: 00000000003526f0
Call Trace:
<TASK>
__kernfs_new_node+0x7b4/0x990 fs/kernfs/dir.c:684
kernfs_new_node+0x13c/0x1e0 fs/kernfs/dir.c:716
kernfs_create_dir_ns+0x4c/0x1a0 fs/kernfs/dir.c:1086
cgroup_create kernel/cgroup/cgroup.c:5859 [inline]
cgroup_mkdir+0x40f/0x12e0 kernel/cgroup/cgroup.c:6007
kernfs_iop_mkdir+0x111/0x190 fs/kernfs/dir.c:1271
vfs_mkdir+0x731/0xb60 fs/namei.c:5130
do_mkdirat+0x442/0x5e0 fs/namei.c:5164
__do_sys_mkdir fs/namei.c:5191 [inline]
__se_sys_mkdir fs/namei.c:5189 [inline]
__x64_sys_mkdir+0xef/0x140 fs/namei.c:5189
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xcd/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f999a38f749
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:00007f999b162038 EFLAGS: 00000246 ORIG_RAX: 0000000000000053
RAX: ffffffffffffffda RBX: 00007f999a5e6090 RCX: 00007f999a38f749
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000200000000000
RBP: 00007f999a413f91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f999a5e6128 R14: 00007f999a5e6090 R15: 00007ffeab19e7e8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:rb_first include/linux/rbtree.h:54 [inline]
RIP: 0010:simple_xattrs_free+0x60/0x1e0 fs/xattr.c:1564
Code: ea 03 80 3c 02 00 0f 85 8b 01 00 00 49 c7 45 00 00 00 00 00 e8 e1 a5 75 ff 4c 89 fa 48 b8 00 00 00 00 00 fc ff df 48 c1 ea 03 <80> 3c 02 00 0f 85 56 01 00 00 48 bd 00 00 00 00 00 fc ff df 49 8b
RSP: 0018:ffffc9000f70fae0 EFLAGS: 00010202
RAX: dffffc0000000000 RBX: ffff88807c948f00 RCX: ffffc9000d3d9000
RDX: 0000000000000007 RSI: ffffffff82493e8f RDI: 0000000000000038
RBP: ffff88807c948f98 R08: 0000000000000005 R09: 0000000000000000
R10: 00000000ffffffea R11: ffffffff82287bd4 R12: 1ffff92001ee1f6b
R13: 0000000000000000 R14: ffff88814d735560 R15: 0000000000000038
FS: 00007f999b1626c0(0000) GS:ffff8881249fd000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f631dbb7198 CR3: 0000000021fa5000 CR4: 00000000003526f0
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 03 80 3c 02 00 0f add 0xf00023c(%rax),%eax
6: 85 8b 01 00 00 49 test %ecx,0x49000001(%rbx)
c: c7 45 00 00 00 00 00 movl $0x0,0x0(%rbp)
13: e8 e1 a5 75 ff call 0xff75a5f9
18: 4c 89 fa mov %r15,%rdx
1b: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
22: fc ff df
25: 48 c1 ea 03 shr $0x3,%rdx
* 29: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2d: 0f 85 56 01 00 00 jne 0x189
33: 48 bd 00 00 00 00 00 movabs $0xdffffc0000000000,%rbp
3a: fc ff df
3d: 49 rex.WB
3e: 8b .byte 0x8b


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