linux-kernel - [PATCH] usb: dvb-usb: fix memory leak in dvb_usb_adapter

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Message-Id: <20210328193219.18647-1-paskripkin@gmail.com>
Date:   Sun, 28 Mar 2021 22:32:19 +0300
From:   Pavel Skripkin <paskripkin@...il.com>
To:     mchehab@...nel.org, sean@...s.org
Cc:     linux-media@...r.kernel.org, linux-kernel@...r.kernel.org,
        Pavel Skripkin <paskripkin@...il.com>,
        syzbot+3c2be7424cea3b932b0e@...kaller.appspotmail.com
Subject: [PATCH] usb: dvb-usb: fix memory leak in dvb_usb_adapter_init

syzbot reported memory leak in dvb-usb. The problem was
in invalid error handling in dvb_usb_adapter_init().

for (n = 0; n < d->props.num_adapters; n++) {
....
	if ((ret = dvb_usb_adapter_stream_init(adap)) ||
		(ret = dvb_usb_adapter_dvb_init(adap, adapter_nrs)) ||
		(ret = dvb_usb_adapter_frontend_init(adap))) {
		return ret;
	}
...
	d->num_adapters_initialized++;
...
}

In case of error in dvb_usb_adapter_dvb_init() or
dvb_usb_adapter_dvb_init() d->num_adapters_initialized won't be
incremented, but dvb_usb_adapter_exit() relies on it:

	for (n = 0; n < d->num_adapters_initialized; n++)

So, allocated objects won't be freed.

Signed-off-by: Pavel Skripkin <paskripkin@...il.com>
Reported-by: syzbot+3c2be7424cea3b932b0e@...kaller.appspotmail.com
---
 drivers/media/usb/dvb-usb/dvb-usb-init.c | 20 ++++++++++++++++----
 1 file changed, 16 insertions(+), 4 deletions(-)

diff --git a/drivers/media/usb/dvb-usb/dvb-usb-init.c b/drivers/media/usb/dvb-usb/dvb-usb-init.c
index c1a7634e27b4..adc8b287326b 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
@@ -79,11 +79,17 @@ static int dvb_usb_adapter_init(struct dvb_usb_device *d, short *adapter_nrs)
 			}
 		}
 
-		if ((ret = dvb_usb_adapter_stream_init(adap)) ||
-			(ret = dvb_usb_adapter_dvb_init(adap, adapter_nrs)) ||
-			(ret = dvb_usb_adapter_frontend_init(adap))) {
+		ret = dvb_usb_adapter_stream_init(adap);
+		if (ret)
 			return ret;
-		}
+
+		ret = dvb_usb_adapter_dvb_init(adap, adapter_nrs);
+		if (ret)
+			goto dvb_init_err;
+
+		ret = dvb_usb_adapter_frontend_init(adap);
+		if (ret)
+			goto frontend_init_err;
 
 		/* use exclusive FE lock if there is multiple shared FEs */
 		if (adap->fe_adap[1].fe)
@@ -103,6 +109,12 @@ static int dvb_usb_adapter_init(struct dvb_usb_device *d, short *adapter_nrs)
 	}
 
 	return 0;
+
+frontend_init_err:
+	dvb_usb_adapter_dvb_exit(adap);
+dvb_init_err:
+	dvb_usb_adapter_stream_exit(adap);
+	return ret;
 }
 
 static int dvb_usb_adapter_exit(struct dvb_usb_device *d)
-- 
2.30.2