[syzbot] [ceph?] [fs?] KASAN: slab-use-after-free Read in ceph_compare_super

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 28c736b0e92e Add linux-next specific files for 20230822
git tree: linux-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11400507a80000
kernel config: https://syzkaller.appspot.com/x/.config?x=20999f779fa96017
dashboard link: https://syzkaller.appspot.com/bug?extid=2b8cbfa6e34e51b6aa50
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1298bdd3a80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11adcca7a80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/37bc881cd0b2/disk-28c736b0.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4512f7892b3d/vmlinux-28c736b0.xz
kernel image: https://storage.googleapis.com/syzbot-assets/052fe1287e05/bzImage-28c736b0.xz

The issue was bisected to:

commit 2c18a63b760a0f68f14cb8bb4c3840bb0b63b73e
Author: Christian Brauner <bra...@kernel.org>
Date: Fri Aug 18 14:00:51 2023 +0000

super: wait until we passed kill super

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=1593bd97a80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=1793bd97a80000
console output: https://syzkaller.appspot.com/x/log.txt?x=1393bd97a80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2b8cbf...@syzkaller.appspotmail.com
Fixes: 2c18a63b760a ("super: wait until we passed kill super")

==================================================================
BUG: KASAN: slab-use-after-free in memcmp+0x1b5/0x1c0 lib/string.c:681
Read of size 8 at addr ffff8880772b2780 by task syz-executor410/5427

CPU: 0 PID: 5427 Comm: syz-executor410 Not tainted 6.5.0-rc7-next-20230822-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/26/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xd9/0x1b0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0xc4/0x620 mm/kasan/report.c:475
kasan_report+0xda/0x110 mm/kasan/report.c:588
memcmp+0x1b5/0x1c0 lib/string.c:681
memcmp include/linux/fortify-string.h:728 [inline]
compare_mount_options fs/ceph/super.c:622 [inline]
ceph_compare_super+0x11a/0x8d0 fs/ceph/super.c:1147
sget_fc+0x582/0x9b0 fs/super.c:778
ceph_get_tree+0x6ea/0x1910 fs/ceph/super.c:1232
vfs_get_tree+0x8c/0x370 fs/super.c:1713
vfs_cmd_create+0x11f/0x2f0 fs/fsopen.c:230
vfs_fsconfig_locked fs/fsopen.c:294 [inline]
__do_sys_fsconfig+0x832/0xb90 fs/fsopen.c:475
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fc6399b13d9
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 51 18 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 b0 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fc639972238 EFLAGS: 00000246 ORIG_RAX: 00000000000001af
RAX: ffffffffffffffda RBX: 00007fc639a3b328 RCX: 00007fc6399b13d9
RDX: 0000000000000000 RSI: 0000000000000006 RDI: 0000000000000003
RBP: 00007fc639a3b320 R08: 0000000000000000 R09: 00007fc6399726c0
R10: 0000000000000000 R11: 0000000000000246 R12: 00007fc639a08064
R13: 0000000000000000 R14: 00007fffb7a44050 R15: 00007fffb7a44138
</TASK>

Allocated by task 5415:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0xa2/0xb0 mm/kasan/common.c:383
kmalloc include/linux/slab.h:599 [inline]
kzalloc include/linux/slab.h:720 [inline]
ceph_init_fs_context+0xc8/0x530 fs/ceph/super.c:1333
alloc_fs_context+0x56c/0x9f0 fs/fs_context.c:294
__do_sys_fsopen fs/fsopen.c:137 [inline]
__se_sys_fsopen fs/fsopen.c:115 [inline]
__x64_sys_fsopen+0xeb/0x230 fs/fsopen.c:115
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 5415:
kasan_save_stack+0x33/0x50 mm/kasan/common.c:45
kasan_set_track+0x25/0x30 mm/kasan/common.c:52
kasan_save_free_info+0x2b/0x40 mm/kasan/generic.c:522
____kasan_slab_free mm/kasan/common.c:236 [inline]
____kasan_slab_free+0x15b/0x1b0 mm/kasan/common.c:200
kasan_slab_free include/linux/kasan.h:164 [inline]
slab_free_hook mm/slub.c:1800 [inline]
slab_free_freelist_hook+0x114/0x1e0 mm/slub.c:1826
slab_free mm/slub.c:3809 [inline]
__kmem_cache_free+0xb8/0x2f0 mm/slub.c:3822
destroy_mount_options fs/ceph/super.c:599 [inline]
destroy_mount_options+0xe9/0x140 fs/ceph/super.c:588
destroy_fs_client+0x1b6/0x2b0 fs/ceph/super.c:860
deactivate_locked_super+0xa0/0x2d0 fs/super.c:454
ceph_get_tree+0x1270/0x1910 fs/ceph/super.c:1267
vfs_get_tree+0x8c/0x370 fs/super.c:1713
vfs_cmd_create+0x11f/0x2f0 fs/fsopen.c:230
vfs_fsconfig_locked fs/fsopen.c:294 [inline]
__do_sys_fsconfig+0x832/0xb90 fs/fsopen.c:475
do_syscall_x64 arch/x86/entry/common.c:50 [inline]
do_syscall_64+0x38/0xb0 arch/x86/entry/common.c:80
entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff8880772b2780
which belongs to the cache kmalloc-96 of size 96
The buggy address is located 0 bytes inside of
freed 96-byte region [ffff8880772b2780, ffff8880772b27e0)

The buggy address belongs to the physical page:
page:ffffea0001dcac80 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x772b2
flags: 0xfff00000000800(slab|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000800 ffff888012c41780 dead000000000122 0000000000000000
raw: 0000000000000000 0000000000200020 00000001ffffffff 0000000000000000
page dumped because: kasan: bad access detected
page_owner tracks the page as allocated
page last allocated via order 0, migratetype Unmovable, gfp_mask 0x12cc0(GFP_KERNEL|__GFP_NOWARN|__GFP_NORETRY), pid 5404, tgid 5400 (syz-executor410), ts 75501157693, free_ts 75473204266
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x2cf/0x340 mm/page_alloc.c:1530
prep_new_page mm/page_alloc.c:1537 [inline]
get_page_from_freelist+0x10d7/0x31b0 mm/page_alloc.c:3213
__alloc_pages+0x1d0/0x4a0 mm/page_alloc.c:4469
alloc_pages+0x1a9/0x270 mm/mempolicy.c:2298
alloc_slab_page mm/slub.c:1870 [inline]
allocate_slab+0x251/0x380 mm/slub.c:2017
new_slab mm/slub.c:2070 [inline]
___slab_alloc+0x8be/0x1570 mm/slub.c:3223
__slab_alloc.constprop.0+0x56/0xa0 mm/slub.c:3322
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x137/0x350 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1022 [inline]
__kmalloc+0x4f/0x100 mm/slab_common.c:1036
kmalloc_array include/linux/slab.h:636 [inline]
ceph_msg_new2+0x34e/0x4f0 net/ceph/messenger.c:1916
msgpool_alloc+0xa8/0x1c0 net/ceph/msgpool.c:17
mempool_init_node+0x2ec/0x5a0 mm/mempool.c:207
mempool_create_node mm/mempool.c:276 [inline]
mempool_create+0x7f/0xd0 mm/mempool.c:261
ceph_msgpool_init+0xd0/0x190 net/ceph/msgpool.c:46
ceph_osdc_init+0x6f9/0xc60 net/ceph/osd_client.c:5193
ceph_create_client net/ceph/ceph_common.c:745 [inline]
ceph_create_client+0x27e/0x360 net/ceph/ceph_common.c:707
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1130 [inline]
free_unref_page_prepare+0x476/0xa40 mm/page_alloc.c:2342
free_unref_page_list+0xe6/0xb30 mm/page_alloc.c:2481
release_pages+0x32a/0x14e0 mm/swap.c:1042
tlb_batch_pages_flush+0x9a/0x190 mm/mmu_gather.c:98
tlb_flush_mmu_free mm/mmu_gather.c:293 [inline]
tlb_flush_mmu mm/mmu_gather.c:300 [inline]
tlb_finish_mmu+0x14b/0x6f0 mm/mmu_gather.c:392
exit_mmap+0x38b/0xa60 mm/mmap.c:3223
__mmput+0x12a/0x4d0 kernel/fork.c:1356
mmput+0x62/0x70 kernel/fork.c:1378
exit_mm kernel/exit.c:567 [inline]
do_exit+0x9b4/0x2a20 kernel/exit.c:861
do_group_exit+0xd4/0x2a0 kernel/exit.c:1024
get_signal+0x23d1/0x27b0 kernel/signal.c:2892
arch_do_signal_or_restart+0x90/0x7f0 arch/x86/kernel/signal.c:309
exit_to_user_mode_loop kernel/entry/common.c:168 [inline]
exit_to_user_mode_prepare+0x11f/0x240 kernel/entry/common.c:204
__syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
syscall_exit_to_user_mode+0x1d/0x60 kernel/entry/common.c:297
do_syscall_64+0x44/0xb0 arch/x86/entry/common.c:86
entry_SYSCALL_64_after_hwframe+0x63/0xcd

Memory state around the buggy address:
ffff8880772b2680: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
ffff8880772b2700: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
>ffff8880772b2780: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
^
ffff8880772b2800: 00 00 00 00 00 00 00 00 00 00 fc fc fc fc fc fc
ffff8880772b2880: fa fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc
==================================================================


---
This report is generated by a bot. It may contain errors.
See https://goo.gl/tpsmEJ for more information about syzbot.
syzbot engineers can be reached at syzk...@googlegroups.com.

syzbot will keep track of this issue. See:
https://goo.gl/tpsmEJ#status for how to communicate with syzbot.
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
If you attach or paste a git patch, syzbot will apply it before testing.

If you want to overwrite bug's subsystems, reply with:
#syz set subsystems: new-subsystem
(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

If you want to undo deduplication, reply with:
#syz undup

[Christian Brauner]

#syz dup: [syzbot] [fuse?] KASAN: slab-use-after-free Read in fuse_test_super

[syzbot]

> #syz dup: [syzbot] [fuse?] KASAN: slab-use-after-free Read in fuse_test_super

can't find the dup bug

[Christian Brauner]

#syz dup: KASAN: slab-use-after-free Read in fuse_test_super

[Hillf Danton]

On Sat, 26 Aug 2023 03:49:56 -0700

> HEAD commit: 28c736b0e92e Add linux-next specific files for 20230822
> git tree: linux-next

> C reproducer: https://syzkaller.appspot.com/x/repro.c?x=11adcca7a80000

Kill super after removing it from @fs_supers.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 28c736b0e92e

--- x/fs/super.c
+++ y/fs/super.c
@@ -451,16 +451,6 @@ void deactivate_locked_super(struct supe
struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
unregister_shrinker(&s->s_shrink);
- fs->kill_sb(s);
-
- /*
- * Since list_lru_destroy() may sleep, we cannot call it from
- * put_super(), where we hold the sb_lock. Therefore we destroy
- * the lru lists right now.
- */
- list_lru_destroy(&s->s_dentry_lru);
- list_lru_destroy(&s->s_inode_lru);
-
/*
* Remove it from @fs_supers so it isn't found by new
* sget{_fc}() walkers anymore. Any concurrent mounter still
@@ -472,6 +462,16 @@ void deactivate_locked_super(struct supe
hlist_del_init(&s->s_instances);
spin_unlock(&sb_lock);

+ fs->kill_sb(s);
+
+ /*
+ * Since list_lru_destroy() may sleep, we cannot call it from
+ * put_super(), where we hold the sb_lock. Therefore we destroy
+ * the lru lists right now.
+ */
+ list_lru_destroy(&s->s_dentry_lru);
+ list_lru_destroy(&s->s_inode_lru);
+
/*
* Let concurrent mounts know that this thing is really dead.
* We don't need @sb->s_umount here as every concurrent caller
--

[syzbot]

Hello,

syzbot tried to test the proposed patch but the build/boot failed:

failed to checkout kernel repo https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git on commit 28c736b0e92e: failed to run ["git" "fetch" "--force" "--tags" "fc608f7504e8b3e110eb6e7b798cef357818c5e1"]: exit status 1
From https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next
+ 28c736b0e92e...2ee82481c392 master -> fc608f7504e8b3e110eb6e7b798cef357818c5e1/master (forced update)
+ 0b86d65557b6...63006762d709 pending-fixes -> fc608f7504e8b3e110eb6e7b798cef357818c5e1/pending-fixes (forced update)
f7757129e3de..2dde18cd1d8f stable -> fc608f7504e8b3e110eb6e7b798cef357818c5e1/stable
* [new tag] next-20230828 -> next-20230828
error: cannot lock ref 'refs/tags/v6.5': 'refs/tags/v6.5/vfs.fixes' exists; cannot create 'refs/tags/v6.5'
! [new tag] v6.5 -> v6.5 (unable to update local ref)
error: some local refs could not be updated; try running
'git remote prune fc608f7504e8b3e110eb6e7b798cef357818c5e1' to remove any old, conflicting branches



Tested on:

commit: [unknown
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 28c736b0e92e

kernel config: https://syzkaller.appspot.com/x/.config?x=20999f779fa96017
dashboard link: https://syzkaller.appspot.com/bug?extid=2b8cbfa6e34e51b6aa50
compiler:

patch: https://syzkaller.appspot.com/x/patch.diff?x=108a71dfa80000

[Hillf Danton]

Kill super after removing it from @fs_supers.

#syz test https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master

--- x/fs/super.c
+++ y/fs/super.c
@@ -451,15 +451,6 @@ void deactivate_locked_super(struct supe

struct file_system_type *fs = s->s_type;
if (atomic_dec_and_test(&s->s_active)) {
unregister_shrinker(&s->s_shrink);
- fs->kill_sb(s);
-
- /*
- * Since list_lru_destroy() may sleep, we cannot call it from
- * put_super(), where we hold the sb_lock. Therefore we destroy
- * the lru lists right now.
- */
- list_lru_destroy(&s->s_dentry_lru);
- list_lru_destroy(&s->s_inode_lru);

/*
* Remove it from @fs_supers so it isn't found by new

@@ -472,6 +463,15 @@ void deactivate_locked_super(struct supe

hlist_del_init(&s->s_instances);
spin_unlock(&sb_lock);

+ fs->kill_sb(s);
+
+ /*
+ * Since list_lru_destroy() may sleep, we cannot call it from
+ * put_super(), where we hold the sb_lock. Therefore we destroy
+ * the lru lists right now.
+ */
+ list_lru_destroy(&s->s_dentry_lru);
+ list_lru_destroy(&s->s_inode_lru);

[syzbot]

Hello,

syzbot has tested the proposed patch and the reproducer did not trigger any issue:

Reported-and-tested-by: syzbot+2b8cbf...@syzkaller.appspotmail.com

Tested on:

commit: 2ee82481 Add linux-next specific files for 20230828
git tree: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git master
console output: https://syzkaller.appspot.com/x/log.txt?x=16f4022fa80000
kernel config: https://syzkaller.appspot.com/x/.config?x=e82a7781f9208c0d
dashboard link: https://syzkaller.appspot.com/bug?extid=2b8cbfa6e34e51b6aa50

compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40

patch: https://syzkaller.appspot.com/x/patch.diff?x=107f7affa80000

Note: testing is done by a robot and is best-effort only.