[syzbot] KASAN: use-after-free Read in kernfs_xattr_get

From: syzbot
Date: Wed Jul 06 2022 - 03:16:37 EST

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Hello,

syzbot found the following issue on:

HEAD commit: 1ce8c443e956 Merge tag 'thermal-5.19-rc5' of git://git.ker..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17851f98080000
kernel config: https://syzkaller.appspot.com/x/.config?x=3a010dbf6a7af480
dashboard link: https://syzkaller.appspot.com/bug?extid=5369664846610db4fa13
compiler: gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.2

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+5369664846610db4fa13@xxxxxxxxxxxxxxxxxxxxxxxxx

usb 8-1: Direct firmware load for ueagle-atm/eagleI.fw failed with error -2
usb 8-1: Falling back to sysfs fallback for: ueagle-atm/eagleI.fw
==================================================================
BUG: KASAN: use-after-free in __kernfs_iattrs fs/kernfs/inode.c:34 [inline]
BUG: KASAN: use-after-free in kernfs_iattrs_noalloc fs/kernfs/inode.c:65 [inline]
BUG: KASAN: use-after-free in kernfs_xattr_get+0x91/0xa0 fs/kernfs/inode.c:303
Read of size 8 at addr ffff88801accf650 by task kworker/0:3/3502

CPU: 0 PID: 3502 Comm: kworker/0:3 Not tainted 5.19.0-rc4-syzkaller-00185-g1ce8c443e956 #0
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.14.0-2 04/01/2014
Workqueue: events request_firmware_work_func
Call Trace:
<TASK>
__dump_stack lib/dump_stack.c:88 [inline]
dump_stack_lvl+0xcd/0x134 lib/dump_stack.c:106
print_address_description.constprop.0.cold+0xeb/0x467 mm/kasan/report.c:313
print_report mm/kasan/report.c:429 [inline]
kasan_report.cold+0xf4/0x1c6 mm/kasan/report.c:491
__kernfs_iattrs fs/kernfs/inode.c:34 [inline]
kernfs_iattrs_noalloc fs/kernfs/inode.c:65 [inline]
kernfs_xattr_get+0x91/0xa0 fs/kernfs/inode.c:303
selinux_kernfs_init_security+0xf2/0x4c0 security/selinux/hooks.c:3509
security_kernfs_init_security+0x48/0xa0 security/security.c:1510
__kernfs_new_node+0x54f/0x8b0 fs/kernfs/dir.c:632
kernfs_new_node fs/kernfs/dir.c:655 [inline]
kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:1010
sysfs_create_dir_ns+0x127/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:63 [inline]
kobject_add_internal+0x2ce/0x900 lib/kobject.c:223
kobject_add_varg lib/kobject.c:358 [inline]
kobject_add+0x150/0x1c0 lib/kobject.c:410
class_dir_create_and_add drivers/base/core.c:2954 [inline]
get_device_parent+0x3d7/0x590 drivers/base/core.c:3009
device_add+0x2af/0x1ea0 drivers/base/core.c:3338
fw_load_sysfs_fallback drivers/base/firmware_loader/fallback.c:82 [inline]
fw_load_from_user_helper drivers/base/firmware_loader/fallback.c:158 [inline]
firmware_fallback_sysfs+0x2da/0xbb0 drivers/base/firmware_loader/fallback.c:234
_request_firmware+0xbd2/0x1190 drivers/base/firmware_loader/main.c:856
request_firmware_work_func+0xdd/0x230 drivers/base/firmware_loader/main.c:1105
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302
</TASK>

Allocated by task 15:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track mm/kasan/common.c:45 [inline]
set_alloc_info mm/kasan/common.c:436 [inline]
__kasan_slab_alloc+0x85/0xb0 mm/kasan/common.c:469
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:750 [inline]
slab_alloc mm/slab.c:3302 [inline]
__kmem_cache_alloc_lru mm/slab.c:3479 [inline]
kmem_cache_alloc+0x265/0x560 mm/slab.c:3499
kmem_cache_zalloc include/linux/slab.h:723 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:593
kernfs_new_node fs/kernfs/dir.c:655 [inline]
kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:1010
sysfs_create_dir_ns+0x127/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:63 [inline]
kobject_add_internal+0x2ce/0x900 lib/kobject.c:223
kobject_add_varg lib/kobject.c:358 [inline]
kobject_add+0x150/0x1c0 lib/kobject.c:410
device_add+0x36d/0x1ea0 drivers/base/core.c:3352
usb_new_device.cold+0x641/0x1091 drivers/usb/core/hub.c:2566
hub_port_connect drivers/usb/core/hub.c:5363 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5507 [inline]
port_event drivers/usb/core/hub.c:5663 [inline]
hub_event+0x25d5/0x4690 drivers/usb/core/hub.c:5745
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
worker_thread+0x665/0x1080 kernel/workqueue.c:2436
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

Freed by task 15:
kasan_save_stack+0x1e/0x40 mm/kasan/common.c:38
kasan_set_track+0x21/0x30 mm/kasan/common.c:45
kasan_set_free_info+0x20/0x30 mm/kasan/generic.c:370
____kasan_slab_free mm/kasan/common.c:366 [inline]
____kasan_slab_free+0x13d/0x180 mm/kasan/common.c:328
kasan_slab_free include/linux/kasan.h:200 [inline]
__cache_free mm/slab.c:3425 [inline]
kmem_cache_free.part.0+0xa9/0x240 mm/slab.c:3735
kernfs_put.part.0+0x2c4/0x540 fs/kernfs/dir.c:547
kernfs_put+0x42/0x50 fs/kernfs/dir.c:521
sysfs_put include/linux/sysfs.h:641 [inline]
__kobject_del+0xea/0x200 lib/kobject.c:589
kobject_del lib/kobject.c:611 [inline]
kobject_del+0x3c/0x60 lib/kobject.c:603
device_del+0x81c/0xc80 drivers/base/core.c:3615
usb_disconnect.cold+0x4ba/0x6ec drivers/usb/core/hub.c:2254
hub_port_connect drivers/usb/core/hub.c:5207 [inline]
hub_port_connect_change drivers/usb/core/hub.c:5507 [inline]
port_event drivers/usb/core/hub.c:5663 [inline]
hub_event+0x1e83/0x4690 drivers/usb/core/hub.c:5745
process_one_work+0x996/0x1610 kernel/workqueue.c:2289
process_scheduled_works kernel/workqueue.c:2352 [inline]
worker_thread+0x854/0x1080 kernel/workqueue.c:2438
kthread+0x2e9/0x3a0 kernel/kthread.c:376
ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:302

The buggy address belongs to the object at ffff88801accf5b0
which belongs to the cache kernfs_node_cache of size 168
The buggy address is located 160 bytes inside of
168-byte region [ffff88801accf5b0, ffff88801accf658)

The buggy address belongs to the physical page:
page:ffffea00006b33c0 refcount:1 mapcount:0 mapping:0000000000000000 index:0xffff88801accfa38 pfn:0x1accf
flags: 0xfff00000000200(slab|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000000200 ffffea00006f2e48 ffffea00006cfe48 ffff888012215000
raw: ffff88801accfa38 ffff88801accf040 0000000100000007 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 0x2420c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_COMP|__GFP_THISNODE), pid 3824, tgid 3815 (syz-executor.3), ts 192593686130, free_ts 192576612676
prep_new_page mm/page_alloc.c:2456 [inline]
get_page_from_freelist+0x1290/0x3b70 mm/page_alloc.c:4198
__alloc_pages_slowpath.constprop.0+0x2e9/0x2160 mm/page_alloc.c:4973
__alloc_pages+0x436/0x510 mm/page_alloc.c:5439
__alloc_pages_node include/linux/gfp.h:587 [inline]
kmem_getpages mm/slab.c:1363 [inline]
cache_grow_begin+0x75/0x350 mm/slab.c:2569
cache_alloc_refill+0x27f/0x380 mm/slab.c:2942
____cache_alloc mm/slab.c:3024 [inline]
____cache_alloc mm/slab.c:3007 [inline]
__do_cache_alloc mm/slab.c:3253 [inline]
slab_alloc mm/slab.c:3295 [inline]
__kmem_cache_alloc_lru mm/slab.c:3479 [inline]
kmem_cache_alloc+0x450/0x560 mm/slab.c:3499
kmem_cache_zalloc include/linux/slab.h:723 [inline]
__kernfs_new_node+0xd4/0x8b0 fs/kernfs/dir.c:593
kernfs_new_node fs/kernfs/dir.c:655 [inline]
kernfs_create_dir_ns+0x9c/0x220 fs/kernfs/dir.c:1010
sysfs_create_dir_ns+0x127/0x290 fs/sysfs/dir.c:59
create_dir lib/kobject.c:63 [inline]
kobject_add_internal+0x2ce/0x900 lib/kobject.c:223
kobject_add_varg lib/kobject.c:358 [inline]
kobject_init_and_add+0x101/0x160 lib/kobject.c:441
nfs_netns_client_alloc fs/nfs/sysfs.c:163 [inline]
nfs_netns_sysfs_setup+0xc4/0x160 fs/nfs/sysfs.c:175
nfs_net_init+0x11/0x20 fs/nfs/inode.c:2341
ops_init+0xaf/0x470 net/core/net_namespace.c:134
setup_net+0x5d1/0xc50 net/core/net_namespace.c:325
copy_net_ns+0x318/0x760 net/core/net_namespace.c:471
page last free stack trace:
reset_page_owner include/linux/page_owner.h:24 [inline]
free_pages_prepare mm/page_alloc.c:1371 [inline]
free_pcp_prepare+0x549/0xd20 mm/page_alloc.c:1421
free_unref_page_prepare mm/page_alloc.c:3343 [inline]
free_unref_page+0x19/0x6a0 mm/page_alloc.c:3438
slab_destroy mm/slab.c:1615 [inline]
slabs_destroy+0x89/0xc0 mm/slab.c:1635
cache_flusharray mm/slab.c:3397 [inline]
___cache_free+0x34e/0x670 mm/slab.c:3460
qlink_free mm/kasan/quarantine.c:168 [inline]
qlist_free_all+0x4f/0x1b0 mm/kasan/quarantine.c:187
kasan_quarantine_reduce+0x180/0x200 mm/kasan/quarantine.c:294
__kasan_slab_alloc+0x97/0xb0 mm/kasan/common.c:446
kasan_slab_alloc include/linux/kasan.h:224 [inline]
slab_post_alloc_hook mm/slab.h:750 [inline]
slab_alloc mm/slab.c:3302 [inline]
__do_kmalloc mm/slab.c:3694 [inline]
__kmalloc_track_caller+0x277/0x4d0 mm/slab.c:3711
kmemdup_nul+0x2d/0xa0 mm/util.c:152
security_context_to_sid_core+0xb4/0x820 security/selinux/ss/services.c:1531
security_context_to_sid+0x35/0x40 security/selinux/ss/services.c:1607
selinux_inode_setxattr+0x36e/0x8a0 security/selinux/hooks.c:3191
security_inode_setxattr+0xf1/0x240 security/security.c:1359
__vfs_setxattr_locked+0xa5/0x260 fs/xattr.c:268
vfs_setxattr+0x13f/0x330 fs/xattr.c:303
setxattr+0x146/0x160 fs/xattr.c:611

Memory state around the buggy address:
ffff88801accf500: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fc fc
ffff88801accf580: fc fc fc fc fc fc fa fb fb fb fb fb fb fb fb fb
>ffff88801accf600: fb fb fb fb fb fb fb fb fb fb fb fc fc fc fc fc
^
ffff88801accf680: fc fc fc fa fb fb fb fb fb fb fb fb fb fb fb fb
ffff88801accf700: fb fb fb fb fb fb fb fb fc fc fc fc fc fc fc fc
==================================================================

---
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Next message: Varad Gautam: "Re: [PATCH] thermal: sysfs: Perform bounds check when storing thermal states"
Previous message: Jimmy Chen (陳永達): "[PATCH 1/2] ARM: dts: imx7d: add dts for UC-8210/8220 hardware"
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