Subject: Re: [syzbot] BUG: corrupted list in nfc_llcp_unregister_device

From: syzbot <[email-masked]>
Date: Fri, 30 Dec 2022 02:41:42 -0800

syzbot has found a reproducer for the following issue on:

HEAD commit:    2258c2dc850b Merge tag 'for-linus' of git://git.kernel.org..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=13c52432480000
kernel config:  https://syzkaller.appspot.com/x/.config?x=555d27e379d75ff1
dashboard link: https://syzkaller.appspot.com/bug?extid=81232c4a81a886e2b580
compiler:       Debian clang version 13.0.1-++20220126092033+75e33f71c2da-1~exp1~20220126212112.63, GNU ld (GNU Binutils for Debian) 2.35.2
syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=170f1214480000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/c7ce28c7893b/disk-2258c2dc.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/467de08be04b/vmlinux-2258c2dc.xz
kernel image: https://storage.googleapis.com/syzbot-assets/d5b6a70e73f2/bzImage-2258c2dc.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: [email-masked]

==================================================================
BUG: KASAN: use-after-free in nfc_llcp_unregister_device+0x65/0x1b0 net/nfc/llcp_core.c:1610
Read of size 8 at addr ffff88802ca38000 by task syz-executor.1/6961

CPU: 1 PID: 6961 Comm: syz-executor.1 Not tainted 6.2.0-rc1-syzkaller-00043-g2258c2dc850b #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/26/2022
Call Trace:
 <TASK>
 __dump_stack lib/dump_stack.c:88 [inline]
 dump_stack_lvl+0x1e3/0x2d0 lib/dump_stack.c:106
 print_address_description+0x74/0x340 mm/kasan/report.c:306
 print_report+0x107/0x220 mm/kasan/report.c:417
 kasan_report+0x139/0x170 mm/kasan/report.c:517
 nfc_llcp_unregister_device+0x65/0x1b0 net/nfc/llcp_core.c:1610
 nfc_unregister_device+0x18a/0x290 net/nfc/core.c:1179
 virtual_ncidev_close+0x55/0x90 drivers/nfc/virtual_ncidev.c:163
 __fput+0x3ba/0x880 fs/file_table.c:320
 task_work_run+0x243/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x134/0x160 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xad/0x110 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x2e/0x60 kernel/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x63/0xcd
RIP: 0033:0x7fd45fe3df5b
Code: 0f 05 48 3d 00 f0 ff ff 77 45 c3 0f 1f 40 00 48 83 ec 18 89 7c 24 0c e8 63 fc ff ff 8b 7c 24 0c 41 89 c0 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 35 44 89 c7 89 44 24 0c e8 a1 fc ff ff 8b 44
RSP: 002b:00007ffd4c417c70 EFLAGS: 00000293 ORIG_RAX: 0000000000000003
RAX: 0000000000000000 RBX: 0000000000000004 RCX: 00007fd45fe3df5b
RDX: 0000001b2e720000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007fd45ffad980 R08: 0000000000000000 R09: 0000000000000010
R10: 00007ffd4c55f0b8 R11: 0000000000000293 R12: 000000000018c31c
R13: 00007ffd4c417d70 R14: 00007fd45ffac120 R15: 0000000000000032
 </TASK>

Allocated by task 6975:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:52
 ____kasan_kmalloc mm/kasan/common.c:371 [inline]
 __kasan_kmalloc+0x97/0xb0 mm/kasan/common.c:380
 kmalloc include/linux/slab.h:580 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 nfc_llcp_register_device+0x51/0x800 net/nfc/llcp_core.c:1566
 nfc_register_device+0x68/0x320 net/nfc/core.c:1124
 nci_register_device+0x7c7/0x900 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0x138/0x1b0 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x346/0x3c0 drivers/char/misc.c:165
 chrdev_open+0x5fb/0x680 fs/char_dev.c:414
 do_dentry_open+0x85f/0x11b0 fs/open.c:882
 do_open fs/namei.c:3557 [inline]
 path_openat+0x25cc/0x2de0 fs/namei.c:3714
 do_filp_open+0x275/0x500 fs/namei.c:3741
 do_sys_openat2+0x13b/0x500 fs/open.c:1310
 do_sys_open fs/open.c:1326 [inline]
 __do_sys_openat fs/open.c:1342 [inline]
 __se_sys_openat fs/open.c:1337 [inline]
 __x64_sys_openat+0x243/0x290 fs/open.c:1337
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x2b/0x70 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

Freed by task 6966:
 kasan_save_stack mm/kasan/common.c:45 [inline]
 kasan_set_track+0x4c/0x70 mm/kasan/common.c:52
 kasan_save_free_info+0x27/0x40 mm/kasan/generic.c:518
 ____kasan_slab_free+0xd6/0x120 mm/kasan/common.c:236
 kasan_slab_free include/linux/kasan.h:177 [inline]
 slab_free_hook mm/slub.c:1781 [inline]
 slab_free_freelist_hook+0x12e/0x1a0 mm/slub.c:1807
 slab_free mm/slub.c:3787 [inline]
 __kmem_cache_free+0x71/0x110 mm/slub.c:3800
 local_release net/nfc/llcp_core.c:173 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nfc_llcp_local_put+0x209/0x230 net/nfc/llcp_core.c:181
 nfc_unregister_device+0x18a/0x290 net/nfc/core.c:1179
 virtual_ncidev_close+0x55/0x90 drivers/nfc/virtual_ncidev.c:163
 __fput+0x3ba/0x880 fs/file_table.c:320
 task_work_run+0x243/0x300 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0x134/0x160 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0xad/0x110 kernel/entry/common.c:203
 __syscall_exit_to_user_mode_work kernel/entry/common.c:285 [inline]
 syscall_exit_to_user_mode+0x2e/0x60 kernel/entry/common.c:296
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

The buggy address belongs to the object at ffff88802ca38000
 which belongs to the cache kmalloc-2k of size 2048
The buggy address is located 0 bytes inside of
 2048-byte region [ffff88802ca38000, ffff88802ca38800)

The buggy address belongs to the physical page:
page:ffffea0000b28e00 refcount:1 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x2ca38
head:ffffea0000b28e00 order:3 compound_mapcount:0 subpages_mapcount:0 compound_pincount:0
anon flags: 0xfff00000010200(slab|head|node=0|zone=1|lastcpupid=0x7ff)
raw: 00fff00000010200 ffff888012842000 0000000000000000 dead000000000001
raw: 0000000000000000 0000000000080008 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 0xd20c0(__GFP_IO|__GFP_FS|__GFP_NOWARN|__GFP_NORETRY|__GFP_COMP|__GFP_NOMEMALLOC), pid 26, tgid 26 (kworker/1:1), ts 13630378390, free_ts 0
 prep_new_page mm/page_alloc.c:2531 [inline]
 get_page_from_freelist+0x72b/0x7a0 mm/page_alloc.c:4283
 __alloc_pages+0x259/0x560 mm/page_alloc.c:5549
 alloc_slab_page+0xbd/0x190 mm/slub.c:1851
 allocate_slab+0x5e/0x3c0 mm/slub.c:1998
 new_slab mm/slub.c:2051 [inline]
 ___slab_alloc+0x7f4/0xeb0 mm/slub.c:3193
 __slab_alloc mm/slub.c:3292 [inline]
 __slab_alloc_node mm/slub.c:3345 [inline]
 slab_alloc_node mm/slub.c:3442 [inline]
 __kmem_cache_alloc_node+0x25b/0x340 mm/slub.c:3491
 kmalloc_trace+0x26/0x60 mm/slab_common.c:1062
 kmalloc include/linux/slab.h:580 [inline]
 kzalloc include/linux/slab.h:720 [inline]
 fw_create_instance+0x59/0x180 drivers/base/firmware_loader/sysfs.c:402
 fw_load_from_user_helper+0xcb/0x1f0 drivers/base/firmware_loader/fallback.c:151
 _request_firmware+0x44b/0x6a0 drivers/base/firmware_loader/main.c:856
 request_firmware_work_func+0x125/0x270 drivers/base/firmware_loader/main.c:1105
 process_one_work+0x81c/0xd10 kernel/workqueue.c:2289
 worker_thread+0xb14/0x1330 kernel/workqueue.c:2436
 kthread+0x266/0x300 kernel/kthread.c:376
 ret_from_fork+0x1f/0x30 arch/x86/entry/entry_64.S:308
page_owner free stack trace missing

Memory state around the buggy address:
 ffff88802ca37f00: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
 ffff88802ca37f80: 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00
>ffff88802ca38000: fa fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
                   ^
 ffff88802ca38080: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
 ffff88802ca38100: fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb fb
==================================================================