[syzbot] [hfs?] KMSAN: uninit-value in hfsplus_rename_cat

syzbot
2023-10-11T11:49:13Z

Hello,

syzbot found the following issue on:

HEAD commit: 82714078aee4 Merge tag 'pm-6.6-rc5' of git://git.kernel.or..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=151aa759680000
kernel config: https://syzkaller.appspot.com/x/.config?x=7a5682d32a74b423
dashboard link: https://syzkaller.appspot.com/bug?extid=93f4402297a457fc6895
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=13095252680000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=123ba911680000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/d1f78c1d4d78/disk-82714078.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/e2a379fc35bb/vmlinux-82714078.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e52238a1bd60/bzImage-82714078.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/286844f77c11/mount_0.gz

Bisection is inconclusive: the issue happens on the oldest tested release.

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=15b3eaee680000
final oops: https://syzkaller.appspot.com/x/report.txt?x=17b3eaee680000
console output: https://syzkaller.appspot.com/x/log.txt?x=13b3eaee680000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+93f4402297a457fc6895@syzkaller.appspotmail.com

and is ignored by this kernel. Remove the mand
option from the mount to silence this warning.
=======================================================
general protection fault, probably for non-canonical address 0xdffffc0000000008: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000040-0x0000000000000047]
CPU: 0 PID: 5030 Comm: syz-executor114 Not tainted 6.6.0-rc4-syzkaller-00229-g82714078aee4 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/06/2023
RIP: 0010:hfsplus_rename_cat+0x4b3/0x1050 fs/hfsplus/catalog.c:480
Code: 60 42 80 3c 20 00 48 8b 5c 24 20 74 05 e8 05 38 81 ff 48 8b 94 24 20 01 00 00 48 83 c3 40 48 89 d8 48 c1 e8 03 48 89 44 24 68 <42> 80 3c 20 00 48 89 54 24 08 74 0d 48 89 df e8 d9 37 81 ff 48 8b
RSP: 0018:ffffc90003a6f780 EFLAGS: 00010202
RAX: 0000000000000008 RBX: 0000000000000040 RCX: ffff8880203e1dc0
RDX: ffff88801fb6f000 RSI: 0000000000000000 RDI: ffffc90003a6f8a0
RBP: ffffc90003a6fbf0 R08: ffffffff8267c274 R09: ad0047e119000000
R10: ad0047e119000000 R11: ad0047e1ad0047e1 R12: dffffc0000000000
R13: ffffc90003a6f86c R14: ffffc90003a6f900 R15: 1ffff9200074df04
FS: 0000555556d88380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd58aeb000 CR3: 0000000027125000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
hfsplus_unlink+0x308/0x790 fs/hfsplus/dir.c:376
vfs_unlink+0x35d/0x5f0 fs/namei.c:4332
do_unlinkat+0x4a7/0x950 fs/namei.c:4398
__do_sys_unlink fs/namei.c:4446 [inline]
__se_sys_unlink fs/namei.c:4444 [inline]
__x64_sys_unlink+0x49/0x50 fs/namei.c:4444
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f9d18b02019
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 f1 17 00 00 90 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:00007ffd58aea948 EFLAGS: 00000246 ORIG_RAX: 0000000000000057
RAX: ffffffffffffffda RBX: 00007f9d18b4b082 RCX: 00007f9d18b02019
RDX: 00007f9d18b02019 RSI: 00007f9d18b012f7 RDI: 00000000200000c0
RBP: 00007f9d18b4b08c R08: 0000000020000000 R09: 0000000020000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007ffd58aea980
R13: 00007ffd58aeaba8 R14: 431bde82d7b634db R15: 00007f9d18b4b03b
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:hfsplus_rename_cat+0x4b3/0x1050 fs/hfsplus/catalog.c:480
Code: 60 42 80 3c 20 00 48 8b 5c 24 20 74 05 e8 05 38 81 ff 48 8b 94 24 20 01 00 00 48 83 c3 40 48 89 d8 48 c1 e8 03 48 89 44 24 68 <42> 80 3c 20 00 48 89 54 24 08 74 0d 48 89 df e8 d9 37 81 ff 48 8b
RSP: 0018:ffffc90003a6f780 EFLAGS: 00010202
RAX: 0000000000000008 RBX: 0000000000000040 RCX: ffff8880203e1dc0
RDX: ffff88801fb6f000 RSI: 0000000000000000 RDI: ffffc90003a6f8a0
RBP: ffffc90003a6fbf0 R08: ffffffff8267c274 R09: ad0047e119000000
R10: ad0047e119000000 R11: ad0047e1ad0047e1 R12: dffffc0000000000
R13: ffffc90003a6f86c R14: ffffc90003a6f900 R15: 1ffff9200074df04
FS: 0000555556d88380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007ffd58aeb000 CR3: 0000000027125000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 1 bytes skipped:
0: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1)
5: 48 8b 5c 24 20 mov 0x20(%rsp),%rbx
a: 74 05 je 0x11
c: e8 05 38 81 ff call 0xff813816
11: 48 8b 94 24 20 01 00 mov 0x120(%rsp),%rdx
18: 00
19: 48 83 c3 40 add $0x40,%rbx
1d: 48 89 d8 mov %rbx,%rax
20: 48 c1 e8 03 shr $0x3,%rax
24: 48 89 44 24 68 mov %rax,0x68(%rsp)
* 29: 42 80 3c 20 00 cmpb $0x0,(%rax,%r12,1) <-- trapping instruction
2e: 48 89 54 24 08 mov %rdx,0x8(%rsp)
33: 74 0d je 0x42
35: 48 89 df mov %rbx,%rdi
38: e8 d9 37 81 ff call 0xff813816
3d: 48 rex.W
3e: 8b .byte 0x8b

---
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For information about bisection process see: https://goo.gl/tpsmEJ#bisection

If the bug is already fixed, let syzbot know by replying with:
#syz fix: exact-commit-title

If you want syzbot to run the reproducer, reply with:
#syz test: git://repo/address.git branch-or-commit-hash
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If you want to overwrite bug's subsystems, reply with:
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(See the list of subsystem names on the web dashboard)

If the bug is a duplicate of another bug, reply with:
#syz dup: exact-subject-of-another-report

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#syz undup