Re: [PATCH 2/2] media: dvb-usb: Fix use-after-free access
On Sun, 31 Jan 2021 16:04:56 +0100, Sean Young wrote: > > Hi Takashi, > > On Fri, Jan 22, 2021 at 04:47:44PM +0100, Robert Foss wrote: > > Hey Takashi, > > > > This patch is generating a checkpatch warning, but I think it is > > spurious and can be ignored. > > The checkpatch warning isn't superious and should really be corrected. It's case-by-case, checkpatch is no bible by itself. In this particular case, it was rather a false-positive of checkpatch: the commit reference including a line-break. This issue has been always annoying and I wish this will be dropped from checkpatch in near future... thanks, Takashi
Re: [PATCH 2/2] media: dvb-usb: Fix use-after-free access
Hi Takashi,
On Fri, Jan 22, 2021 at 04:47:44PM +0100, Robert Foss wrote:
> Hey Takashi,
>
> This patch is generating a checkpatch warning, but I think it is
> spurious and can be ignored.
The checkpatch warning isn't superious and should really be corrected.
>
> Other than that, this looks good to me.
> Reviewed-by: Robert Foss
>
> On Wed, 20 Jan 2021 at 12:51, Takashi Iwai wrote:
> >
> > 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
> > BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1181104
> > Cc:
> > Signed-off-by: Takashi Iwai
Thank you for your patch. Unfortunately, it depends on the first patch
in the series, which I think has problems (see email about this).
Thanks
Sean
> > ---
> > 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 5befec87f26a..07ff9b4d2f34 100644
> > --- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
> > +++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
> > @@ -255,27 +255,30 @@ int dvb_usb_device_init(struct usb_interface *intf,
> > if (du != NULL)
> > *du = NULL;
> >
> > - if ((desc = dvb_usb_find_device(udev, props, )) == NULL) {
> > + d = kzalloc(sizeof(struct dvb_usb_device), GFP_KERNEL);
> > + if (!d) {
> > + err("no memory for 'struct dvb_usb_device'");
> > + return -ENOMEM;
> > + }
> > +
> > + memcpy(>props, props, sizeof(struct dvb_usb_device_properties));
> > +
> > + desc = dvb_usb_find_device(udev, >props, );
> > + 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(>props, props, sizeof(struct dvb_usb_device_properties));
> > d->desc = desc;
> > d->owner = owner;
> >
> > --
> > 2.26.2
> >
Re: [PATCH 2/2] media: dvb-usb: Fix use-after-free access
Hey Takashi,
This patch is generating a checkpatch warning, but I think it is
spurious and can be ignored.
Other than that, this looks good to me.
Reviewed-by: Robert Foss
On Wed, 20 Jan 2021 at 12:51, Takashi Iwai wrote:
>
> 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
> BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1181104
> Cc:
> Signed-off-by: Takashi Iwai
> ---
> 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 5befec87f26a..07ff9b4d2f34 100644
> --- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
> +++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
> @@ -255,27 +255,30 @@ int dvb_usb_device_init(struct usb_interface *intf,
> if (du != NULL)
> *du = NULL;
>
> - if ((desc = dvb_usb_find_device(udev, props, )) == NULL) {
> + d = kzalloc(sizeof(struct dvb_usb_device), GFP_KERNEL);
> + if (!d) {
> + err("no memory for 'struct dvb_usb_device'");
> + return -ENOMEM;
> + }
> +
> + memcpy(>props, props, sizeof(struct dvb_usb_device_properties));
> +
> + desc = dvb_usb_find_device(udev, >props, );
> + 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(>props, props, sizeof(struct dvb_usb_device_properties));
> d->desc = desc;
> d->owner = owner;
>
> --
> 2.26.2
>
[PATCH 2/2] media: dvb-usb: Fix use-after-free access
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
BugLink: http://bugzilla.opensuse.org/show_bug.cgi?id=1181104
Cc:
Signed-off-by: Takashi Iwai
---
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 5befec87f26a..07ff9b4d2f34 100644
--- a/drivers/media/usb/dvb-usb/dvb-usb-init.c
+++ b/drivers/media/usb/dvb-usb/dvb-usb-init.c
@@ -255,27 +255,30 @@ int dvb_usb_device_init(struct usb_interface *intf,
if (du != NULL)
*du = NULL;
- if ((desc = dvb_usb_find_device(udev, props, )) == NULL) {
+ d = kzalloc(sizeof(struct dvb_usb_device), GFP_KERNEL);
+ if (!d) {
+ err("no memory for 'struct dvb_usb_device'");
+ return -ENOMEM;
+ }
+
+ memcpy(>props, props, sizeof(struct dvb_usb_device_properties));
+
+ desc = dvb_usb_find_device(udev, >props, );
+ 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(>props, props, sizeof(struct dvb_usb_device_properties));
d->desc = desc;
d->owner = owner;
--
2.26.2
