KASAN: use-after-free Read in udf_get_fileident

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 8034e99d1a01 Linux 4.14.266
git tree: linux-4.14.y
console output: https://syzkaller.appspot.com/x/log.txt?x=13ab9b44700000
kernel config: https://syzkaller.appspot.com/x/.config?x=647e517ce784ab05
dashboard link: https://syzkaller.appspot.com/bug?extid=20e0018f5cf946534e8c
compiler: gcc version 10.2.1 20210110 (Debian 10.2.1-6)
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16f33454700000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=14a1d64a700000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+20e001...@syzkaller.appspotmail.com

UDF-fs: INFO Mounting volume 'LinuxUDF', timestamp 2020/09/19 18:44 (1000)
==================================================================
BUG: KASAN: use-after-free in udf_get_fileident+0x1ea/0x200 fs/udf/directory.c:178
Read of size 2 at addr ffff8880980024fc by task syz-executor244/7960

CPU: 1 PID: 7960 Comm: syz-executor244 Not tainted 4.14.266-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:17 [inline]
dump_stack+0x1b2/0x281 lib/dump_stack.c:58
print_address_description.cold+0x54/0x1d3 mm/kasan/report.c:252
kasan_report_error.cold+0x8a/0x191 mm/kasan/report.c:351
kasan_report mm/kasan/report.c:409 [inline]
__asan_report_load_n_noabort+0x6b/0x80 mm/kasan/report.c:440
udf_get_fileident+0x1ea/0x200 fs/udf/directory.c:178
udf_fileident_read+0x4b9/0x1840 fs/udf/directory.c:36
udf_readdir+0x4d0/0x11f0 fs/udf/dir.c:129
iterate_dir+0x1a0/0x5e0 fs/readdir.c:52
SYSC_getdents64 fs/readdir.c:358 [inline]
SyS_getdents64+0x125/0x230 fs/readdir.c:339
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb
RIP: 0033:0x7efd8c27c5b9
RSP: 002b:00007ffd8620d638 EFLAGS: 00000246 ORIG_RAX: 00000000000000d9
RAX: ffffffffffffffda RBX: 0030656c69662f2e RCX: 00007efd8c27c5b9
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000004
RBP: 00007efd8c23be50 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 00007efd8c23bee0
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000

Allocated by task 6234:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_kmalloc+0xeb/0x160 mm/kasan/kasan.c:551
kmem_cache_alloc_trace+0x131/0x3d0 mm/slab.c:3618
kmalloc include/linux/slab.h:488 [inline]
kzalloc include/linux/slab.h:661 [inline]
kernfs_fop_open+0x266/0xc40 fs/kernfs/file.c:648
do_dentry_open+0x44b/0xec0 fs/open.c:777
vfs_open+0x105/0x220 fs/open.c:888
do_last fs/namei.c:3428 [inline]
path_openat+0x628/0x2970 fs/namei.c:3569
do_filp_open+0x179/0x3c0 fs/namei.c:3603
do_sys_open+0x296/0x410 fs/open.c:1081
do_syscall_64+0x1d5/0x640 arch/x86/entry/common.c:292
entry_SYSCALL_64_after_hwframe+0x46/0xbb

Freed by task 6234:
save_stack mm/kasan/kasan.c:447 [inline]
set_track mm/kasan/kasan.c:459 [inline]
kasan_slab_free+0xc3/0x1a0 mm/kasan/kasan.c:524
__cache_free mm/slab.c:3496 [inline]
kfree+0xc9/0x250 mm/slab.c:3815
kernfs_fop_release+0x10e/0x180 fs/kernfs/file.c:783
__fput+0x25f/0x7a0 fs/file_table.c:210
task_work_run+0x11f/0x190 kernel/task_work.c:113
tracehook_notify_resume include/linux/tracehook.h:191 [inline]
exit_to_usermode_loop+0x1ad/0x200 arch/x86/entry/common.c:164
prepare_exit_to_usermode arch/x86/entry/common.c:199 [inline]
syscall_return_slowpath arch/x86/entry/common.c:270 [inline]
do_syscall_64+0x4a3/0x640 arch/x86/entry/common.c:297
entry_SYSCALL_64_after_hwframe+0x46/0xbb

The buggy address belongs to the object at ffff888098002340
which belongs to the cache kmalloc-512 of size 512
The buggy address is located 444 bytes inside of
512-byte region [ffff888098002340, ffff888098002540)
The buggy address belongs to the page:
page:ffffea0002600080 count:1 mapcount:0 mapping:ffff8880980020c0 index:0xffff888098002340
flags: 0xfff00000000100(slab)
raw: 00fff00000000100 ffff8880980020c0 ffff888098002340 0000000100000005
raw: ffffea00025bd9a0 ffff88813fe64738 ffff88813fe74940 0000000000000000
page dumped because: kasan: bad access detected

Memory state around the buggy address:
ffff888098002380: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888098002400: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888098002480: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888098002500: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
ffff888098002580: fc fc fc fc fc fc fc fc 00 00 00 00 00 00 00 00
==================================================================


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