pps: fix warning in pps_register_cdev when register device fail
[ Upstream commit b0531cdba5029f897da5156815e3bdafe1e9b88d ]
Similar to previous commit 2a934fdb01db ("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 c79a39dc8d06 ("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 Now the comment is outdated,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.
BUG=b/456103711
TEST=presubmit
RELEASE_NOTE=Fixed CVE-2025-40070 in the Linux kernel.
cos-patch: security-moderate
Link: https://lore.kernel.org/all/20250827065010.3208525-1-wangliang74@huawei.com/
Fixes: c79a39dc8d06 ("pps: Fix a use-after-free")
Change-Id: Idfc9ada481829b0e428ad9885628b74fa3df09d9
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>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Kernel CVE Triage Automation <cloud-image-kernel-cve-triage-automation@prod.google.com>
Reviewed-on: https://cos-review.googlesource.com/c/third_party/kernel/+/116242
Reviewed-by: Daniel Velasquez <rdvelasquez@google.com>
Reviewed-by: Dom Huh <domhuh@google.com>
Tested-by: Cusky Presubmit Bot <presubmit@cos-infra-prod.iam.gserviceaccount.com>
diff --git a/drivers/pps/kapi.c b/drivers/pps/kapi.c
index 92d1b62..e938987 100644
--- a/drivers/pps/kapi.c
+++ b/drivers/pps/kapi.c
@@ -109,16 +109,13 @@ struct pps_device *pps_register_source(struct pps_source_info *info,
if (err < 0) {
pr_err("%s: unable to create char device\n",
info->name);
- goto kfree_pps;
+ goto pps_register_source_exit;
}
dev_dbg(&pps->dev, "new PPS source %s\n", info->name);
return pps;
-kfree_pps:
- kfree(pps);
-
pps_register_source_exit:
pr_err("%s: unable to register source\n", info->name);
diff --git a/drivers/pps/pps.c b/drivers/pps/pps.c
index e168995..9539695 100644
--- a/drivers/pps/pps.c
+++ b/drivers/pps/pps.c
@@ -375,6 +375,7 @@ int pps_register_cdev(struct pps_device *pps)
pps->info.name);
err = -EBUSY;
}
+ kfree(pps);
goto out_unlock;
}
pps->id = err;
@@ -384,13 +385,11 @@ int pps_register_cdev(struct pps_device *pps)
pps->dev.devt = MKDEV(pps_major, pps->id);
dev_set_drvdata(&pps->dev, pps);
dev_set_name(&pps->dev, "pps%d", pps->id);
+ pps->dev.release = pps_device_destruct;
err = device_register(&pps->dev);
if (err)
goto free_idr;
- /* Override the release function with our own */
- pps->dev.release = pps_device_destruct;
-
pr_debug("source %s got cdev (%d:%d)\n", pps->info.name, pps_major,
pps->id);
