From: Duoming Zhou <duoming@zju.edu.cn> stable inclusion from stable-v6.6.111 commit 71ed8b81a4906cb785966910f39cf7f5ad60a69e category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/ID22QL CVE: CVE-2025-39994 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 40b7a19f321e65789612ebaca966472055dab48c ] The original code uses cancel_delayed_work() in xc5000_release(), which does not guarantee that the delayed work item timer_sleep has fully completed if it was already running. This leads to use-after-free scenarios where xc5000_release() may free the xc5000_priv while timer_sleep is still active and attempts to dereference the xc5000_priv. A typical race condition is illustrated below: CPU 0 (release thread) | CPU 1 (delayed work callback) xc5000_release() | xc5000_do_timer_sleep() cancel_delayed_work() | hybrid_tuner_release_state(priv) | kfree(priv) | | priv = container_of() // UAF Replace cancel_delayed_work() with cancel_delayed_work_sync() to ensure that the timer_sleep is properly canceled before the xc5000_priv memory is deallocated. A deadlock concern was considered: xc5000_release() is called in a process context and is not holding any locks that the timer_sleep work item might also need. Therefore, the use of the _sync() variant is safe here. This bug was initially identified through static analysis. Fixes: f7a27ff1fb77 ("[media] xc5000: delay tuner sleep to 5 seconds") Cc: stable@vger.kernel.org Signed-off-by: Duoming Zhou <duoming@zju.edu.cn> Signed-off-by: Hans Verkuil <hverkuil+cisco@kernel.org> [hverkuil: fix typo in Subject: tunner -> tuner] Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: drivers/media/tuners/xc5000.c [commit f82dc869220d has not been backported.] Signed-off-by: Jiacheng Yu <yujiacheng3@huawei.com> --- drivers/media/tuners/xc5000.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/media/tuners/xc5000.c b/drivers/media/tuners/xc5000.c index 2182e5b7b606..de34fc9a9f2f 100644 --- a/drivers/media/tuners/xc5000.c +++ b/drivers/media/tuners/xc5000.c @@ -1305,7 +1305,7 @@ static void xc5000_release(struct dvb_frontend *fe) mutex_lock(&xc5000_list_mutex); if (priv) { - cancel_delayed_work(&priv->timer_sleep); + cancel_delayed_work_sync(&priv->timer_sleep); if (priv->firmware) { release_firmware(priv->firmware); priv->firmware = NULL; -- 2.43.0