[syzbot] KASAN: null-ptr-deref Write in udf_write_fi

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 1a61b828566f Merge tag 'char-misc-6.0-rc7' of git://git.ke..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=153836e4880000
kernel config: https://syzkaller.appspot.com/x/.config?x=122d7bd4fc8e0ecb
dashboard link: https://syzkaller.appspot.com/bug?extid=8a5a459f324d510ea15a
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16e7fb54880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14864288880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/367e34e7ff83/disk-1a61b828.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/91a2819fe451/vmlinux-1a61b828.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8a5a45...@syzkaller.appspotmail.com

UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2022/09/12 12:00 (1000)
==================================================================
BUG: KASAN: null-ptr-deref in udf_write_fi+0x380/0xff0 fs/udf/namei.c:91
Write of size 18446744073709551572 at addr 0000000000000020 by task syz-executor377/3607

CPU: 0 PID: 3607 Comm: syz-executor377 Not tainted 6.0.0-rc6-syzkaller-00309-g1a61b828566f #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/26/2022
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
kasan_report+0xb1/0x1e0 mm/kasan/report.c:495
check_region_inline mm/kasan/generic.c:183 [inline]
kasan_check_range+0x13d/0x180 mm/kasan/generic.c:189
memset+0x20/0x40 mm/kasan/shadow.c:44
udf_write_fi+0x380/0xff0 fs/udf/namei.c:91
udf_rename+0x45e/0x1250 fs/udf/namei.c:1173
vfs_rename+0x115e/0x1a90 fs/namei.c:4756
do_renameat2+0xb5e/0xc80 fs/namei.c:4907
__do_sys_rename fs/namei.c:4953 [inline]
__se_sys_rename fs/namei.c:4951 [inline]
__x64_sys_rename+0x7d/0xa0 fs/namei.c:4951
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7f7e9cef1b69
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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe69a64f88 EFLAGS: 00000246 ORIG_RAX: 0000000000000052
RAX: ffffffffffffffda RBX: 0000000000000002 RCX: 00007f7e9cef1b69
RDX: 0000000000000f90 RSI: 0000000020000880 RDI: 00000000200007c0
RBP: 00007ffe69a64f90 R08: 0000000000000002 R09: 0000000000003731
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000004
R13: 00007ffe69a64ff8 R14: 00007ffe69a65030 R15: 0000000000000003
</TASK>
==================================================================


---
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[syzbot]

syzbot suspects this issue was fixed by commit:

commit e9109a92d2a95889498bed3719cd2318892171a2
Author: Jan Kara <ja...@suse.cz>
Date: Thu Oct 6 14:41:23 2022 +0000

udf: Convert udf_rename() to new directory iteration code

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1191f00f480000
start commit: 55be6084c8e0 Merge tag 'timers-core-2022-10-05' of git://g..
git tree: upstream
kernel config: https://syzkaller.appspot.com/x/.config?x=df75278aabf0681a
dashboard link: https://syzkaller.appspot.com/bug?extid=8a5a459f324d510ea15a
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=100a46c2880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=116a4e72880000

If the result looks correct, please mark the issue as fixed by replying with:

#syz fix: udf: Convert udf_rename() to new directory iteration code

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

[Dmitry Vyukov]

Looks sane: