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Date:   Mon, 24 Apr 2023 00:20:46 -0700
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Subject: [syzbot] [nfc?] KCSAN: data-race in __list_del_entry_valid / nfc_llcp_register_device
From:   syzbot <syzbot+742c192afb1b2a0cbe86@syzkaller.appspotmail.com>
To:     davem@davemloft.net, edumazet@google.com,
        krzysztof.kozlowski@linaro.org, kuba@kernel.org,
        linux-kernel@vger.kernel.org, linux-nfc@lists.01.org,
        netdev@vger.kernel.org, pabeni@redhat.com,
        syzkaller-bugs@googlegroups.com
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Hello,

syzbot found the following issue on:

HEAD commit:    44149752e998 Merge tag 'cgroup-for-6.3-rc6-fixes' of git:/..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1682221fc80000
kernel config:  https://syzkaller.appspot.com/x/.config?x=710057cbb8def08c
dashboard link: https://syzkaller.appspot.com/bug?extid=742c192afb1b2a0cbe86
compiler:       Debian clang version 15.0.7, GNU ld (GNU Binutils for Debian) 2.35.2

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

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/7bfa303f05cc/disk-44149752.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/4e8ea8730409/vmlinux-44149752.xz
kernel image: https://storage.googleapis.com/syzbot-assets/e584bce13ba7/bzImage-44149752.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+742c192afb1b2a0cbe86@syzkaller.appspotmail.com

==================================================================
BUG: KCSAN: data-race in __list_del_entry_valid / nfc_llcp_register_device

read to 0xffff88810318c808 of 8 bytes by task 28453 on cpu 1:
 __list_del_entry_valid+0x15/0xe0 lib/list_debug.c:46
 __list_del_entry include/linux/list.h:134 [inline]
 list_del include/linux/list.h:148 [inline]
 local_release net/nfc/llcp_core.c:172 [inline]
 kref_put include/linux/kref.h:65 [inline]
 nfc_llcp_local_put net/nfc/llcp_core.c:182 [inline]
 nfc_llcp_unregister_device+0x7e/0x130 net/nfc/llcp_core.c:1620
 nfc_unregister_device+0xe6/0x130 net/nfc/core.c:1179
 nci_unregister_device+0x14c/0x160 net/nfc/nci/core.c:1303
 virtual_ncidev_close+0x30/0x50 drivers/nfc/virtual_ncidev.c:163
 __fput+0x245/0x570 fs/file_table.c:321
 ____fput+0x15/0x20 fs/file_table.c:349
 task_work_run+0x123/0x160 kernel/task_work.c:179
 resume_user_mode_work include/linux/resume_user_mode.h:49 [inline]
 exit_to_user_mode_loop+0xd1/0xe0 kernel/entry/common.c:171
 exit_to_user_mode_prepare+0x6c/0xb0 kernel/entry/common.c:204
 __syscall_exit_to_user_mode_work kernel/entry/common.c:286 [inline]
 syscall_exit_to_user_mode+0x26/0x140 kernel/entry/common.c:297
 do_syscall_64+0x4d/0xc0 arch/x86/entry/common.c:86
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

write to 0xffff88810318c808 of 8 bytes by task 28459 on cpu 0:
 __list_add include/linux/list.h:72 [inline]
 list_add include/linux/list.h:88 [inline]
 nfc_llcp_register_device+0x3e4/0x440 net/nfc/llcp_core.c:1604
 nfc_register_device+0x67/0x190 net/nfc/core.c:1124
 nci_register_device+0x4e6/0x570 net/nfc/nci/core.c:1257
 virtual_ncidev_open+0xdc/0x140 drivers/nfc/virtual_ncidev.c:148
 misc_open+0x1fd/0x230 drivers/char/misc.c:165
 chrdev_open+0x349/0x3c0 fs/char_dev.c:414
 do_dentry_open+0x5b3/0x930 fs/open.c:920
 vfs_open+0x47/0x50 fs/open.c:1051
 do_open fs/namei.c:3560 [inline]
 path_openat+0x17e6/0x1d00 fs/namei.c:3715
 do_filp_open+0xf6/0x200 fs/namei.c:3742
 do_sys_openat2+0xb5/0x2a0 fs/open.c:1348
 do_sys_open fs/open.c:1364 [inline]
 __do_sys_openat fs/open.c:1380 [inline]
 __se_sys_openat fs/open.c:1375 [inline]
 __x64_sys_openat+0xf3/0x120 fs/open.c:1375
 do_syscall_x64 arch/x86/entry/common.c:50 [inline]
 do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80
 entry_SYSCALL_64_after_hwframe+0x63/0xcd

value changed: 0xffffffff85eac670 -> 0xdead000000000122

Reported by Kernel Concurrency Sanitizer on:
CPU: 0 PID: 28459 Comm: syz-executor.0 Not tainted 6.3.0-rc6-syzkaller-00138-g44149752e998 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/30/2023
==================================================================


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