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Wed, 05 Aug 2026 13:47:42 -0700 (PDT) From: Shuangpeng Bai To: Mauro Carvalho Chehab Cc: Hyunwoo Kim , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Shuangpeng Bai , stable@vger.kernel.org Subject: [PATCH] media: dvb-core: Fix UAF in dvb_ca_en50221_io_release() Date: Wed, 5 Aug 2026 16:47:04 -0400 Message-ID: <20260805204704.3789917-1-shuangpeng.kernel@gmail.com> X-Mailer: git-send-email 2.43.0 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit dvb_ca_en50221_io_release() drops the open file's reference to ca before testing ca->exit and unlocking ca->remove_mutex. If dvb_ca_en50221_release() concurrently drops the initial reference, the close path's put can be the final one and free ca. The following ca->exit access and mutex_unlock() then operate on freed memory. Keep the close path's reference until it has finished accessing ca and released remove_mutex. The reference also keeps ca->dvbdev alive while the wake-up condition is handled. Fixes: 280a8ab81733 ("media: dvb-core: Fix use-after-free due to race condition at dvb_ca_en50221") Cc: stable@vger.kernel.org Signed-off-by: Shuangpeng Bai --- drivers/media/dvb-core/dvb_ca_en50221.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/media/dvb-core/dvb_ca_en50221.c b/drivers/media/dvb-core/dvb_ca_en50221.c index 1b91ebb8f667..86df28c4aa4b 100644 --- a/drivers/media/dvb-core/dvb_ca_en50221.c +++ b/drivers/media/dvb-core/dvb_ca_en50221.c @@ -1787,8 +1787,6 @@ static int dvb_ca_en50221_io_release(struct inode *inode, struct file *file) module_put(ca->pub->owner); - dvb_ca_private_put(ca); - if (dvbdev->users == 1 && ca->exit == 1) { mutex_unlock(&ca->remove_mutex); wake_up(&dvbdev->wait_queue); @@ -1796,6 +1794,8 @@ static int dvb_ca_en50221_io_release(struct inode *inode, struct file *file) mutex_unlock(&ca->remove_mutex); } + dvb_ca_private_put(ca); + return err; } -- 2.43.0