Similar to previous commit 2a934fdb01 ("media: v4l2-dev: fix error
handling in __video_register_device()"), the release hook should be set
before device_register(). Otherwise, when device_register() return error
and put_device() try to callback the release function, the below warning
may happen.
------------[ cut here ]------------
WARNING: CPU: 1 PID: 4760 at drivers/base/core.c:2567 device_release+0x1bd/0x240 drivers/base/core.c:2567
Modules linked in:
CPU: 1 UID: 0 PID: 4760 Comm: syz.4.914 Not tainted 6.17.0-rc3+ #1 NONE
RIP: 0010:device_release+0x1bd/0x240 drivers/base/core.c:2567
Call Trace:
<TASK>
kobject_cleanup+0x136/0x410 lib/kobject.c:689
kobject_release lib/kobject.c:720 [inline]
kref_put include/linux/kref.h:65 [inline]
kobject_put+0xe9/0x130 lib/kobject.c:737
put_device+0x24/0x30 drivers/base/core.c:3797
pps_register_cdev+0x2da/0x370 drivers/pps/pps.c:402
pps_register_source+0x2f6/0x480 drivers/pps/kapi.c:108
pps_tty_open+0x190/0x310 drivers/pps/clients/pps-ldisc.c:57
tty_ldisc_open+0xa7/0x120 drivers/tty/tty_ldisc.c:432
tty_set_ldisc+0x333/0x780 drivers/tty/tty_ldisc.c:563
tiocsetd drivers/tty/tty_io.c:2429 [inline]
tty_ioctl+0x5d1/0x1700 drivers/tty/tty_io.c:2728
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:598 [inline]
__se_sys_ioctl fs/ioctl.c:584 [inline]
__x64_sys_ioctl+0x194/0x210 fs/ioctl.c:584
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x5f/0x2a0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x76/0x7e
</TASK>
Before commit c79a39dc8d ("pps: Fix a use-after-free"),
pps_register_cdev() call device_create() to create pps->dev, which will
init dev->release to device_create_release(). Now the comment is outdated,
just remove it.
Thanks for the reminder from Calvin Owens, 'kfree_pps' should be removed
in pps_register_source() to avoid a double free in the failure case.
Link: https://lore.kernel.org/all/20250827065010.3208525-1-wangliang74@huawei.com/
Fixes: c79a39dc8d ("pps: Fix a use-after-free")
Signed-off-by: Wang Liang <wangliang74@huawei.com>
Reviewed-By: Calvin Owens <calvin@wbinvd.org>
Link: https://lore.kernel.org/r/20250830075023.3498174-1-wangliang74@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
b0531cdba5