[syzbot] [btrfs?] KASAN: slab-out-of-bounds Read in getname_kernel (2)

syzbot
2023-12-18T14:43:27Z

Hello,

syzbot found the following issue on:

HEAD commit: 3bd7d7488169 Merge tag 'io_uring-6.7-2023-12-15' of git://..
git tree: upstream
console+strace: https://syzkaller.appspot.com/x/log.txt?x=13732cc6e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=53ec3da1d259132f
dashboard link: https://syzkaller.appspot.com/bug?extid=33f23b49ac24f986c9e8
compiler: Debian clang version 15.0.6, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16d8ba06e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=136fd5b2e80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/99b3f103aa0b/disk-3bd7d748.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/32f8e3e696ce/vmlinux-3bd7d748.xz
kernel image: https://storage.googleapis.com/syzbot-assets/cb20a5445c11/bzImage-3bd7d748.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/4f5365674997/mount_0.gz

The issue was bisected to:

commit 9974d37ea75f01b47d16072b5dad305bd8d23fcc
Author: Liu Jian <liujian56@huawei.com>
Date: Tue Jun 28 12:36:16 2022 +0000

skmsg: Fix invalid last sg check in sk_msg_recvmsg()

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=172b998ae80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=14ab998ae80000
console output: https://syzkaller.appspot.com/x/log.txt?x=10ab998ae80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+33f23b49ac24f986c9e8@syzkaller.appspotmail.com
Fixes: 9974d37ea75f ("skmsg: Fix invalid last sg check in sk_msg_recvmsg()")

BTRFS info (device loop0): clearing compat-ro feature flag for FREE_SPACE_TREE_VALID (0x2)
==================================================================
BUG: KASAN: slab-out-of-bounds in strlen+0x58/0x70 lib/string.c:418
Read of size 1 at addr ffff88801d7f2a28 by task syz-executor424/5057

CPU: 1 PID: 5057 Comm: syz-executor424 Not tainted 6.7.0-rc5-syzkaller-00200-g3bd7d7488169 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0x1e7/0x2d0 lib/dump_stack.c:106
print_address_description mm/kasan/report.c:364 [inline]
print_report+0x163/0x540 mm/kasan/report.c:475
kasan_report+0x142/0x170 mm/kasan/report.c:588
strlen+0x58/0x70 lib/string.c:418
getname_kernel+0x1d/0x2e0 fs/namei.c:226
kern_path+0x1d/0x50 fs/namei.c:2609
lookup_bdev block/bdev.c:979 [inline]
bdev_open_by_path+0xd1/0x540 block/bdev.c:901
btrfs_init_dev_replace_tgtdev fs/btrfs/dev-replace.c:260 [inline]
btrfs_dev_replace_start fs/btrfs/dev-replace.c:638 [inline]
btrfs_dev_replace_by_ioctl+0x41b/0x2010 fs/btrfs/dev-replace.c:747
btrfs_ioctl_dev_replace+0x2c9/0x390 fs/btrfs/ioctl.c:3299
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f8e8ffdc079
Code: 28 00 00 00 75 05 48 83 c4 28 c3 e8 61 17 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 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007ffe15cbe138 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
RAX: ffffffffffffffda RBX: 00007ffe15cbe308 RCX: 00007f8e8ffdc079
RDX: 0000000020000540 RSI: 00000000ca289435 RDI: 0000000000000005
RBP: 00007f8e90054610 R08: 00007ffe15cbe308 R09: 00007ffe15cbe308
R10: 00007ffe15cbe308 R11: 0000000000000246 R12: 0000000000000001
R13: 00007ffe15cbe2f8 R14: 0000000000000001 R15: 0000000000000001
</TASK>

Allocated by task 5057:
kasan_save_stack mm/kasan/common.c:45 [inline]
kasan_set_track+0x4f/0x70 mm/kasan/common.c:52
____kasan_kmalloc mm/kasan/common.c:374 [inline]
__kasan_kmalloc+0x98/0xb0 mm/kasan/common.c:383
kasan_kmalloc include/linux/kasan.h:198 [inline]
__do_kmalloc_node mm/slab_common.c:1007 [inline]
__kmalloc_node_track_caller+0xb1/0x190 mm/slab_common.c:1027
memdup_user+0x2b/0xc0 mm/util.c:197
btrfs_ioctl_dev_replace+0xb8/0x390 fs/btrfs/ioctl.c:3286
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:871 [inline]
__se_sys_ioctl+0xf8/0x170 fs/ioctl.c:857
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x45/0x110 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b

The buggy address belongs to the object at ffff88801d7f2000
which belongs to the cache kmalloc-4k of size 4096
The buggy address is located 0 bytes to the right of
allocated 2600-byte region [ffff88801d7f2000, ffff88801d7f2a28)

The buggy address belongs to the physical page:
page:ffffea000075fc00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x1d7f0
head:ffffea000075fc00 order:3 entire_mapcount:0 nr_pages_mapped:0 pincount:0
flags: 0xfff00000000840(slab|head|node=0|zone=1|lastcpupid=0x7ff)
page_type: 0xffffffff()
raw: 00fff00000000840 ffff888012c42140 ffffea00007b5600 0000000000000002
raw: 0000000000000000 0000000080040004 00000001ffffffff 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 0xd2040(__GFP_IO|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 4716, tgid 4716 (ifup), ts 29920494589, free_ts 29905444571
set_page_owner include/linux/page_owner.h:31 [inline]
post_alloc_hook+0x1e6/0x210 mm/page_alloc.c:1537
prep_new_page mm/page_alloc.c:1544 [inline]
get_page_from_freelist+0x33ea/0x3570 mm/page_alloc.c:3312
__alloc_pages+0x255/0x680 mm/page_alloc.c:4568
alloc_pages_mpol+0x3de/0x640 mm/mempolicy.c:2133
alloc_slab_page+0x6a/0x170 mm/slub.c:1870
allocate_slab mm/slub.c:2017 [inline]
new_slab+0x84/0x2f0 mm/slub.c:2070
___slab_alloc+0xc8a/0x1330 mm/slub.c:3223
__slab_alloc mm/slub.c:3322 [inline]
__slab_alloc_node mm/slub.c:3375 [inline]
slab_alloc_node mm/slub.c:3468 [inline]
__kmem_cache_alloc_node+0x21d/0x300 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa2/0x1a0 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [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+0x63/0xa0 security/security.c:2836
do_dentry_open+0x327/0x1590 fs/open.c:935
do_open fs/namei.c:3622 [inline]
path_openat+0x2849/0x3290 fs/namei.c:3779
do_filp_open+0x234/0x490 fs/namei.c:3809
do_sys_openat2+0x13e/0x1d0 fs/open.c:1440
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1137 [inline]
free_unref_page_prepare+0x931/0xa60 mm/page_alloc.c:2347
free_unref_page+0x37/0x3f0 mm/page_alloc.c:2487
discard_slab mm/slub.c:2116 [inline]
__unfreeze_partials+0x1e0/0x220 mm/slub.c:2655
put_cpu_partial+0x17b/0x250 mm/slub.c:2731
__slab_free+0x2b6/0x390 mm/slub.c:3679
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x75/0xe0 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x14b/0x160 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x23/0x70 mm/kasan/common.c:305
kasan_slab_alloc include/linux/kasan.h:188 [inline]
slab_post_alloc_hook+0x6c/0x3c0 mm/slab.h:763
slab_alloc_node mm/slub.c:3478 [inline]
__kmem_cache_alloc_node+0x1d0/0x300 mm/slub.c:3517
__do_kmalloc_node mm/slab_common.c:1006 [inline]
__kmalloc+0xa2/0x1a0 mm/slab_common.c:1020
kmalloc include/linux/slab.h:604 [inline]
tomoyo_realpath_from_path+0xcf/0x5e0 security/tomoyo/realpath.c:251
tomoyo_get_realpath security/tomoyo/file.c:151 [inline]
tomoyo_path_perm+0x2b7/0x730 security/tomoyo/file.c:822
security_inode_getattr+0xd3/0x120 security/security.c:2153
vfs_getattr+0x46/0x430 fs/stat.c:173
vfs_fstat fs/stat.c:198 [inline]
vfs_fstatat+0xd6/0x190 fs/stat.c:295

Memory state around the buggy address:
ffff88801d7f2900: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
ffff88801d7f2980: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88801d7f2a00: 00 00 00 00 00 fc fc fc fc fc fc fc fc fc fc fc
^
ffff88801d7f2a80: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
ffff88801d7f2b00: fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc fc
==================================================================

---
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