Re: [syzbot] [jffs2?] [nilfs?] KASAN: slab-use-after-free Read in jffs2_garbage_collect_pass

From: syzbot
Date: Mon Apr 22 2024 - 01:23:16 EST


Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
KASAN: slab-use-after-free Read in jffs2_garbage_collect_pass

==================================================================
BUG: KASAN: slab-use-after-free in __mutex_lock_common kernel/locking/mutex.c:587 [inline]
BUG: KASAN: slab-use-after-free in __mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752
Read of size 8 at addr ffff888061ba6130 by task jffs2_gcd_mtd0/5501

CPU: 0 PID: 5501 Comm: jffs2_gcd_mtd0 Not tainted 6.9.0-rc5-syzkaller-ged30a4a51bb1 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/27/2024
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x241/0x360 lib/dump_stack.c:114
print_address_description mm/kasan/report.c:377 [inline]
print_report+0x169/0x550 mm/kasan/report.c:488
kasan_report+0x143/0x180 mm/kasan/report.c:601
__mutex_lock_common kernel/locking/mutex.c:587 [inline]
__mutex_lock+0xfe/0xd70 kernel/locking/mutex.c:752
jffs2_garbage_collect_pass+0xae/0x2120 fs/jffs2/gc.c:134
jffs2_garbage_collect_thread+0x651/0x6e0 fs/jffs2/background.c:155
kthread+0x2f0/0x390 kernel/kthread.c:388
ret_from_fork+0x4b/0x80 arch/x86/kernel/process.c:147
ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:244
</TASK>

Allocated by task 5495:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
poison_kmalloc_redzone mm/kasan/common.c:370 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:387
kasan_kmalloc include/linux/kasan.h:211 [inline]
kmalloc_trace+0x1db/0x360 mm/slub.c:3997
kmalloc include/linux/slab.h:628 [inline]
kzalloc include/linux/slab.h:749 [inline]
jffs2_init_fs_context+0x4f/0xc0 fs/jffs2/super.c:313
alloc_fs_context+0x68a/0x800 fs/fs_context.c:318
do_new_mount+0x160/0xb40 fs/namespace.c:3331
do_mount fs/namespace.c:3692 [inline]
__do_sys_mount fs/namespace.c:3898 [inline]
__se_sys_mount+0x2d9/0x3c0 fs/namespace.c:3875
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Freed by task 5428:
kasan_save_stack mm/kasan/common.c:47 [inline]
kasan_save_track+0x3f/0x80 mm/kasan/common.c:68
kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:579
poison_slab_object+0xa6/0xe0 mm/kasan/common.c:240
__kasan_slab_free+0x37/0x60 mm/kasan/common.c:256
kasan_slab_free include/linux/kasan.h:184 [inline]
slab_free_hook mm/slub.c:2106 [inline]
slab_free mm/slub.c:4280 [inline]
kfree+0x153/0x3a0 mm/slub.c:4390
deactivate_locked_super+0xc4/0x130 fs/super.c:472
cleanup_mnt+0x426/0x4c0 fs/namespace.c:1267
task_work_run+0x24f/0x310 kernel/task_work.c:180
resume_user_mode_work include/linux/resume_user_mode.h:50 [inline]
exit_to_user_mode_loop kernel/entry/common.c:114 [inline]
exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
__syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
syscall_exit_to_user_mode+0x168/0x370 kernel/entry/common.c:218
do_syscall_64+0x102/0x240 arch/x86/entry/common.c:89
entry_SYSCALL_64_after_hwframe+0x77/0x7f

The buggy address belongs to the object at ffff888061ba6000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 304 bytes inside of
freed 4096-byte region [ffff888061ba6000, ffff888061ba7000)

The buggy address belongs to the physical page:
page: refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x61ba0
head: order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff80000000840(slab|head|node=0|zone=1|lastcpupid=0xfff)
page_type: 0xffffffff()
raw: 00fff80000000840 ffff888015042140 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
head: 00fff80000000840 ffff888015042140 dead000000000122 0000000000000000
head: 0000000000000000 0000000000040004 00000001ffffffff 0000000000000000
head: 00fff80000000003 ffffea000186e801 dead000000000122 00000000ffffffff
head: 0000000800000000 0000000000000000 00000000ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 3, migratetype Unmovable, gfp_mask 0x1d2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC|__GFP_HARDWALL), pid 5494, tgid -833224093 (syz-executor.0), ts 5495, free_ts 89333775363
set_page_owner include/linux/page_owner.h:32 [inline]
post_alloc_hook+0x1ea/0x210 mm/page_alloc.c:1534
prep_new_page mm/page_alloc.c:1541 [inline]
get_page_from_freelist+0x3410/0x35b0 mm/page_alloc.c:3317
__alloc_pages+0x256/0x6c0 mm/page_alloc.c:4575
__alloc_pages_node include/linux/gfp.h:238 [inline]
alloc_pages_node include/linux/gfp.h:261 [inline]
alloc_slab_page+0x5f/0x160 mm/slub.c:2175
allocate_slab mm/slub.c:2338 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2391
___slab_alloc+0xc73/0x1260 mm/slub.c:3525
__slab_alloc mm/slub.c:3610 [inline]
__slab_alloc_node mm/slub.c:3663 [inline]
slab_alloc_node mm/slub.c:3835 [inline]
__do_kmalloc_node mm/slub.c:3965 [inline]
__kmalloc+0x2e5/0x4a0 mm/slub.c:3979
kmalloc include/linux/slab.h:632 [inline]
tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_check_open_permission+0x255/0x500 security/tomoyo/file.c:771
security_file_open+0x69/0x570 security/security.c:2961
do_dentry_open+0x327/0x15a0 fs/open.c:942
do_open fs/namei.c:3642 [inline]
path_openat+0x2860/0x3240 fs/namei.c:3799
do_filp_open+0x235/0x490 fs/namei.c:3826
do_sys_openat2+0x13e/0x1d0 fs/open.c:1406
do_sys_open fs/open.c:1421 [inline]
__do_sys_openat fs/open.c:1437 [inline]
__se_sys_openat fs/open.c:1432 [inline]
__x64_sys_openat+0x247/0x2a0 fs/open.c:1432
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
page last free pid 5445 tgid 5445 stack trace:
reset_page_owner include/linux/page_owner.h:25 [inline]
free_pages_prepare mm/page_alloc.c:1141 [inline]
free_unref_page_prepare+0x97b/0xaa0 mm/page_alloc.c:2347
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
__slab_free+0x31b/0x3d0 mm/slub.c:4192
qlink_free mm/kasan/quarantine.c:163 [inline]
qlist_free_all+0x5e/0xc0 mm/kasan/quarantine.c:179
kasan_quarantine_reduce+0x14f/0x170 mm/kasan/quarantine.c:286
__kasan_slab_alloc+0x23/0x80 mm/kasan/common.c:322
kasan_slab_alloc include/linux/kasan.h:201 [inline]
slab_post_alloc_hook mm/slub.c:3798 [inline]
slab_alloc_node mm/slub.c:3845 [inline]
kmem_cache_alloc+0x174/0x340 mm/slub.c:3852
getname_flags+0xbd/0x4f0 fs/namei.c:139
getname fs/namei.c:218 [inline]
__do_sys_rename fs/namei.c:5084 [inline]
__se_sys_rename fs/namei.c:5082 [inline]
__x64_sys_rename+0x5f/0xa0 fs/namei.c:5082
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xf5/0x240 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x77/0x7f

Memory state around the buggy address:
ffff888061ba6000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061ba6080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
>ffff888061ba6100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
^
ffff888061ba6180: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
ffff888061ba6200: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================


Tested on:

commit: ed30a4a5 Linux 6.9-rc5
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=133bb3ab180000
kernel config: https://syzkaller.appspot.com/x/.config?x=ab247b9c410b3012
dashboard link: https://syzkaller.appspot.com/bug?extid=e84662c5f30b8c401437
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40

Note: no patches were applied.