[PATCH v2 1/2] media: dvb-usb: Fix memory leak at error in dvb_usb_device_init()

From: Takashi Iwai
Date: Mon Feb 01 2021 - 03:33:54 EST


dvb_usb_device_init() allocates a dvb_usb_device object, but it
doesn't release the object by itself even at errors. The object is
released in the callee side (dvb_usb_init()) in some error cases via
dvb_usb_exit() call, but it also missed the object free in other error
paths. And, the caller (it's only dvb_usb_device_init()) doesn't seem
caring the resource management as well, hence those memories are
leaked.

This patch assures releasing the memory at the error path in
dvb_usb_device_init(). Now dvb_usb_init() frees the resources it
allocated but leaves the passed dvb_usb_device object intact. In
turn, the dvb_usb_device object is released in dvb_usb_device_init()
instead.
We could use dvb_usb_exit() function for releasing everything in the
callee (as it was used for some error cases in the original code), but
releasing the passed object in the callee is non-intuitive and
error-prone. So I took this approach (which is more standard in Linus
kernel code) although it ended with a bit more open codes.

Along with the change, the patch makes sure that USB intfdata is reset
and don't return the bogus pointer to the caller of
dvb_usb_device_init() at the error path, too.

Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Takashi Iwai <tiwai@xxxxxxx>
---
v1->v2: Fix double-free and reorganize the code

drivers/media/usb/dvb-usb/dvb-usb-init.c | 47 ++++++++++++++++--------
1 file changed, 31 insertions(+), 16 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..c78158d12540 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
@@ -158,22 +158,20 @@ static int dvb_usb_init(struct dvb_usb_device *d, short *adapter_nums)

if (d->props.priv_init != NULL) {
ret = d->props.priv_init(d);
- if (ret != 0) {
- kfree(d->priv);
- d->priv = NULL;
- return ret;
- }
+ if (ret != 0)
+ goto err_priv_init;
}
}

/* check the capabilities and set appropriate variables */
dvb_usb_device_power_ctrl(d, 1);

- if ((ret = dvb_usb_i2c_init(d)) ||
- (ret = dvb_usb_adapter_init(d, adapter_nums))) {
- dvb_usb_exit(d);
- return ret;
- }
+ ret = dvb_usb_i2c_init(d);
+ if (ret)
+ goto err_i2c_init;
+ ret = dvb_usb_adapter_init(d, adapter_nums);
+ if (ret)
+ goto err_adapter_init;

if ((ret = dvb_usb_remote_init(d)))
err("could not initialize remote control.");
@@ -181,6 +179,17 @@ static int dvb_usb_init(struct dvb_usb_device *d, short *adapter_nums)
dvb_usb_device_power_ctrl(d, 0);

return 0;
+
+err_adapter_init:
+ dvb_usb_adapter_exit(d);
+err_i2c_init:
+ dvb_usb_i2c_exit(d);
+ if (d->priv && d->props.priv_destroy)
+ d->props.priv_destroy(d);
+err_priv_init:
+ kfree(d->priv);
+ d->priv = NULL;
+ return ret;
}

/* determine the name and the state of the just found USB device */
@@ -281,15 +290,21 @@ int dvb_usb_device_init(struct usb_interface *intf,

usb_set_intfdata(intf, d);

- if (du != NULL)
+ ret = dvb_usb_init(d, adapter_nums);
+ if (ret) {
+ info("%s error while loading driver (%d)", desc->name, ret);
+ goto error;
+ }
+
+ if (du)
*du = d;

- ret = dvb_usb_init(d, adapter_nums);
+ info("%s successfully initialized and connected.", desc->name);
+ return 0;

- if (ret == 0)
- info("%s successfully initialized and connected.", desc->name);
- else
- info("%s error while loading driver (%d)", desc->name, ret);
+ error:
+ usb_set_intfdata(intf, NULL);
+ kfree(d);
return ret;
}
EXPORT_SYMBOL(dvb_usb_device_init);
--
2.26.2