[syzbot] BUG: unable to handle kernel NULL pointer dereference in udf_rename

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: bbed346d5a96 Merge branch 'for-next/core' into for-kernelci
git tree: git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux.git for-kernelci
console output: https://syzkaller.appspot.com/x/log.txt?x=17a63346880000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a4a45d2d827c1e
dashboard link: https://syzkaller.appspot.com/bug?extid=17fcf98a689ff64f669b
compiler: Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
userspace arch: arm64
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=100d5e2e880000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=17fb8b39880000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/e8e91bc79312/disk-bbed346d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/c1cb3fb3b77e/vmlinux-bbed346d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/b990eb66b8ea/mount_0.gz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+17fcf9...@syzkaller.appspotmail.com

loop0: detected capacity change from 0 to 2048
UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2022/09/12 12:00 (1000)
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
Mem abort info:
ESR = 0x0000000096000046
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x06: level 2 translation fault
Data abort info:
ISV = 0, ISS = 0x00000046
CM = 0, WnR = 1
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000109085000
[0000000000000020] pgd=0800000106b68003, p4d=0800000106b68003, pud=0800000106b69003, pmd=0000000000000000
Internal error: Oops: 0000000096000046 [#1] PREEMPT SMP
Modules linked in:
CPU: 0 PID: 3036 Comm: syz-executor863 Not tainted 6.0.0-rc7-syzkaller-18095-gbbed346d5a96 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 09/30/2022
pstate: 80400005 (Nzcv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : __memset+0x84/0x188 arch/arm64/lib/memset.S:100
lr : udf_write_fi+0x268/0x4e0
sp : ffff800012a53a50
x29: ffff800012a53a70 x28: 00000000000000d6 x27: 00000000000000d6
x26: 00000000fffffff0 x25: 0000000000000000 x24: 0000000000000006
x23: 00000000ffffffd4 x22: fffffffffffffff4 x21: ffff800012a53b40
x20: ffff800012a53b00 x19: 0000000000000003 x18: 0000000000000021
x17: 0000000000000000 x16: ffff80000db49158 x15: ffff0000c6401a80
x14: 0000000000000010 x13: 0000000000000000 x12: ffff0000c6401a80
x11: ff80800008d1bd1c x10: 0000000000000000 x9 : ffff800008d1bd1c
x8 : 0000000000000020 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000010
x2 : ffffffffffffffd4 x1 : 0000000000000000 x0 : 0000000000000020
Call trace:
__memset+0x84/0x188 arch/arm64/lib/memset.S:98
udf_delete_entry fs/udf/namei.c:577 [inline]
udf_rename+0x47c/0x6d0 fs/udf/namei.c:1173
vfs_rename+0x59c/0x7f8 fs/namei.c:4756
do_renameat2+0x490/0x758 fs/namei.c:4907
__do_sys_renameat2 fs/namei.c:4940 [inline]
__se_sys_renameat2 fs/namei.c:4937 [inline]
__arm64_sys_renameat2+0x6c/0x88 fs/namei.c:4937
__invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
invoke_syscall arch/arm64/kernel/syscall.c:52 [inline]
el0_svc_common+0x138/0x220 arch/arm64/kernel/syscall.c:142
do_el0_svc+0x48/0x164 arch/arm64/kernel/syscall.c:206
el0_svc+0x58/0x150 arch/arm64/kernel/entry-common.c:636
el0t_64_sync_handler+0x84/0xf0 arch/arm64/kernel/entry-common.c:654
el0t_64_sync+0x18c/0x190 arch/arm64/kernel/entry.S:581
Code: 54000060 5400006b a8811d07 a8811d07 (a8811d07)
---[ end trace 0000000000000000 ]---
----------------
Code disassembly (best guess):
0: 54000060 b.eq 0xc // b.none
4: 5400006b b.lt 0x10 // b.tstop
8: a8811d07 stp x7, x7, [x8], #16
c: a8811d07 stp x7, x7, [x8], #16
* 10: a8811d07 stp x7, x7, [x8], #16 <-- trapping instruction


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[syzbot]

Auto-closing this bug as obsolete.
No recent activity, existing reproducers are no longer triggering the issue.