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media: dvb-core: Fix double free in dvb_register_device()

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commit 6b0d0477fce747d4137aa65856318b55fba72198 upstream.

In function dvb_register_device() -> dvb_register_media_device() ->
dvb_create_media_entity(), dvb->entity is allocated and initialized. If
the initialization fails, it frees the dvb->entity, and return an error
code. The caller takes the error code and handles the error by calling
dvb_media_device_free(), which unregisters the entity and frees the
field again if it is not NULL. As dvb->entity may not NULLed in
dvb_create_media_entity() when the allocation of dvbdev->pad fails, a
double free may occur. This may also cause an Use After free in
media_device_unregister_entity().

Fix this by storing NULL to dvb->entity when it is freed.

Link: https://lore.kernel.org/linux-media/20220426052921.2088416-1-keitasuzuki.park@sslab.ics.keio.ac.jp
Fixes: fcd5ce4b39 ("media: dvb-core: fix a memory leak bug")
Cc: stable@vger.kernel.org
Cc: Wenwen Wang <wenwen@cs.uga.edu>
Signed-off-by: Keita Suzuki <keitasuzuki.park@sslab.ics.keio.ac.jp>
Signed-off-by: Mauro Carvalho Chehab <mchehab@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Keita Suzuki 2022-04-26 06:29:19 +01:00 committed by Greg Kroah-Hartman
parent 50c2379f87
commit b21f62b49e
1 changed files with 1 additions and 0 deletions
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drivers/media/dvb-core/dvbdev.c
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@ -345,6 +345,7 @@ static int dvb_create_media_entity(struct dvb_device *dvbdev,
GFP_KERNEL); GFP_KERNEL);
if (!dvbdev->pads) { if (!dvbdev->pads) {
kfree(dvbdev->entity); kfree(dvbdev->entity);
dvbdev->entity = NULL;
return -ENOMEM; return -ENOMEM;
} }
} }