[syzbot] [overlayfs?] general protection fault in clone_private_mount

From: syzbot
Date: Thu Feb 06 2025 - 08:32:32 EST

Hello,

syzbot found the following issue on:

HEAD commit: 808eb958781e Add linux-next specific files for 20250206
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=126e33df980000
kernel config: https://syzkaller.appspot.com/x/.config?x=88b25e5d30d576e4
dashboard link: https://syzkaller.appspot.com/bug?extid=62dfea789a2cedac1298
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16346df8580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=117e80e4580000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/493ef93f2e5f/disk-808eb958.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/b41757cd41c9/vmlinux-808eb958.xz
kernel image: https://storage.googleapis.com/syzbot-assets/24f456104aad/bzImage-808eb958.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+62dfea789a2cedac1298@xxxxxxxxxxxxxxxxxxxxxxxxx

Oops: general protection fault, probably for non-canonical address 0xdffffc0000000009: 0000 [#1] PREEMPT SMP KASAN PTI
KASAN: null-ptr-deref in range [0x0000000000000048-0x000000000000004f]
CPU: 0 UID: 0 PID: 5834 Comm: syz-executor772 Not tainted 6.14.0-rc1-next-20250206-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 12/27/2024
RIP: 0010:is_anon_ns fs/mount.h:159 [inline]
RIP: 0010:clone_private_mount+0x184/0x3e0 fs/namespace.c:2425
Code: 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 48 83 c3 48 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 4d 89 fc 74 08 48 89 df e8 db dd e4 ff 48 8b 1b 31 ff
RSP: 0018:ffffc90003e2f958 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000048 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff888032eb2710
RBP: 0000000000000000 R08: ffffffff8ea81ca7 R09: 1ffffffff1d50394
R10: dffffc0000000000 R11: fffffbfff1d50395 R12: ffff888032eb2700
R13: ffff888032eb2720 R14: 1ffff11006b34091 R15: ffff8880359a0488
FS: 0000555584629380(0000) GS:ffff8880b8600000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000200000001000 CR3: 00000000786c2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
ovl_get_layers fs/overlayfs/super.c:1061 [inline]
ovl_get_lowerstack fs/overlayfs/super.c:1156 [inline]
ovl_fill_super+0x1a24/0x3560 fs/overlayfs/super.c:1404
vfs_get_super fs/super.c:1280 [inline]
get_tree_nodev+0xb7/0x140 fs/super.c:1299
vfs_get_tree+0x90/0x2b0 fs/super.c:1814
do_new_mount+0x2be/0xb40 fs/namespace.c:3659
do_mount fs/namespace.c:3999 [inline]
__do_sys_mount fs/namespace.c:4210 [inline]
__se_sys_mount+0x2d6/0x3c0 fs/namespace.c:4187
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf3/0x230 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f9d7cd98329
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffdbd4bd438 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007f9d7cd98329
RDX: 0000200000000180 RSI: 0000200000000140 RDI: 0000000000000000
RBP: 00007f9d7ce0b610 R08: 00002000000001c0 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffdbd4bd608 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:is_anon_ns fs/mount.h:159 [inline]
RIP: 0010:clone_private_mount+0x184/0x3e0 fs/namespace.c:2425
Code: 89 d8 48 83 c4 10 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc 48 83 c3 48 48 89 d8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df <80> 3c 08 00 4d 89 fc 74 08 48 89 df e8 db dd e4 ff 48 8b 1b 31 ff
RSP: 0018:ffffc90003e2f958 EFLAGS: 00010206
RAX: 0000000000000009 RBX: 0000000000000048 RCX: dffffc0000000000
RDX: 0000000000000001 RSI: 0000000000000008 RDI: ffff888032eb2710
RBP: 0000000000000000 R08: ffffffff8ea81ca7 R09: 1ffffffff1d50394
R10: dffffc0000000000 R11: fffffbfff1d50395 R12: ffff888032eb2700
R13: ffff888032eb2720 R14: 1ffff11006b34091 R15: ffff8880359a0488
FS: 0000555584629380(0000) GS:ffff8880b8700000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000066c7e0 CR3: 00000000786c2000 CR4: 00000000003526f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess):
0: 89 d8 mov %ebx,%eax
2: 48 83 c4 10 add $0x10,%rsp
6: 5b pop %rbx
7: 41 5c pop %r12
9: 41 5d pop %r13
b: 41 5e pop %r14
d: 41 5f pop %r15
f: 5d pop %rbp
10: c3 ret
11: cc int3
12: cc int3
13: cc int3
14: cc int3
15: 48 83 c3 48 add $0x48,%rbx
19: 48 89 d8 mov %rbx,%rax
1c: 48 c1 e8 03 shr $0x3,%rax
20: 48 b9 00 00 00 00 00 movabs $0xdffffc0000000000,%rcx
27: fc ff df
* 2a: 80 3c 08 00 cmpb $0x0,(%rax,%rcx,1) <-- trapping instruction
2e: 4d 89 fc mov %r15,%r12
31: 74 08 je 0x3b
33: 48 89 df mov %rbx,%rdi
36: e8 db dd e4 ff call 0xffe4de16
3b: 48 8b 1b mov (%rbx),%rbx
3e: 31 ff xor %edi,%edi


---
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