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Subject: media: dvb-usb: Fix use-after-free access Author: Takashi Iwai tiwai@suse.de Date: Mon Feb 1 09:32:47 2021 +0100

dvb_usb_device_init() copies the properties to the own data, so that the callers can release the original properties later (as done in the commit 299c7007e936 ("media: dw2102: Fix memleak on sequence of probes")). However, it also stores dev->desc pointer that is a reference to the original properties data. Since dev->desc is referred later, it may result in use-after-free, in the worst case, leading to a kernel Oops as reported.

This patch addresses the problem by allocating and copying the properties at first, then get the desc from the copied properties.

Reported-and-tested-by: Stefan Seyfried seife+kernel@b1-systems.com BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1181104

Reviewed-by: Robert Foss robert.foss@linaro.org Cc: stable@vger.kernel.org Signed-off-by: Takashi Iwai tiwai@suse.de Signed-off-by: Sean Young sean@mess.org Signed-off-by: Mauro Carvalho Chehab mchehab+huawei@kernel.org

drivers/media/usb/dvb-usb/dvb-usb-init.c | 23 +++++++++++++---------- 1 file changed, 13 insertions(+), 10 deletions(-)

---

diff --git a/drivers/media/usb/dvb-usb/dvb-usb-init.c b/drivers/media/usb/dvb-usb/dvb-usb-init.c index c78158d12540..6c9e3290af56 100644 --- a/drivers/media/usb/dvb-usb/dvb-usb-init.c +++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c @@ -264,27 +264,30 @@ int dvb_usb_device_init(struct usb_interface *intf, if (du != NULL) *du = NULL;

- if ((desc = dvb_usb_find_device(udev, props, &cold)) == NULL) { + d = kzalloc(sizeof(*d), GFP_KERNEL); + if (!d) { + err("no memory for 'struct dvb_usb_device'"); + return -ENOMEM; + } + + memcpy(&d->props, props, sizeof(struct dvb_usb_device_properties)); + + desc = dvb_usb_find_device(udev, &d->props, &cold); + if (!desc) { deb_err("something went very wrong, device was not found in current device list - let's see what comes next.\n"); - return -ENODEV; + ret = -ENODEV; + goto error; }

if (cold) { info("found a '%s' in cold state, will try to load a firmware", desc->name); ret = dvb_usb_download_firmware(udev, props); if (!props->no_reconnect || ret != 0) - return ret; + goto error; }

info("found a '%s' in warm state.", desc->name); - d = kzalloc(sizeof(struct dvb_usb_device), GFP_KERNEL); - if (d == NULL) { - err("no memory for 'struct dvb_usb_device'"); - return -ENOMEM; - } - d->udev = udev; - memcpy(&d->props, props, sizeof(struct dvb_usb_device_properties)); d->desc = desc; d->owner = owner;