On Sun, Apr 03, 2022 at 10:52:07PM -0400, Charlie Sands wrote:
> This patch fixes sparse warnings about the memcmp function unsafely
> accessing userspace memory without first copying it to kernel space.
>
> Signed-off-by: Charlie Sands <[email protected]>
> ---
>
> V2: Fixed checkpatch.pl warning and changed variable name as suggested
> by Greg K. H. and improved error checking on the "copy_from_user" function as
> suggested by Pavel Skripkin.
>
> drivers/staging/r8188eu/os_dep/ioctl_linux.c | 21 ++++++++++++--------
> 1 file changed, 13 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/staging/r8188eu/os_dep/ioctl_linux.c b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> index 7df213856d66..4b4eec2bde96 100644
> --- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> +++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> @@ -3233,23 +3233,28 @@ static int rtw_p2p_get(struct net_device *dev,
> struct iw_request_info *info,
> union iwreq_data *wrqu, char *extra)
> {
> - if (!memcmp(wrqu->data.pointer, "status", 6)) {
> + char wrqu_data[9];
> +
> + if (copy_from_user(wrqu_data, wrqu->data.pointer, 9) != 0)
> + return 0;
return -EFAULT; We can't assume that that user wants to copy 9 bytes
especially when they're passing a 4 character + NUL string.
This is a custom ioctl. Called from ioctl_private_iw_point().
I think if you try to dereference a user pointer like this then it will
cause a crash, right? So that means no one has ever tested or used this
code and we hopefully we can just delete it?
regards,
dan carpenter
On luned? 4 aprile 2022 12:50:41 CEST Dan Carpenter wrote:
> On Sun, Apr 03, 2022 at 10:52:07PM -0400, Charlie Sands wrote:
> > This patch fixes sparse warnings about the memcmp function unsafely
> > accessing userspace memory without first copying it to kernel space.
> >
> > Signed-off-by: Charlie Sands <[email protected]>
> > ---
> >
> > V2: Fixed checkpatch.pl warning and changed variable name as suggested
> > by Greg K. H. and improved error checking on the "copy_from_user" function as
> > suggested by Pavel Skripkin.
> >
> > drivers/staging/r8188eu/os_dep/ioctl_linux.c | 21 ++++++++++++--------
> > 1 file changed, 13 insertions(+), 8 deletions(-)
> >
> > diff --git a/drivers/staging/r8188eu/os_dep/ioctl_linux.c b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> > index 7df213856d66..4b4eec2bde96 100644
> > --- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> > +++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> > @@ -3233,23 +3233,28 @@ static int rtw_p2p_get(struct net_device *dev,
> > struct iw_request_info *info,
> > union iwreq_data *wrqu, char *extra)
> > {
> > - if (!memcmp(wrqu->data.pointer, "status", 6)) {
> > + char wrqu_data[9];
> > +
> > + if (copy_from_user(wrqu_data, wrqu->data.pointer, 9) != 0)
> > + return 0;
>
> return -EFAULT; We can't assume that that user wants to copy 9 bytes
> especially when they're passing a 4 character + NUL string.
>
> This is a custom ioctl. Called from ioctl_private_iw_point().
>
> I think if you try to dereference a user pointer like this then it will
> cause a crash, right? So that means no one has ever tested or used this
> code and we hopefully we can just delete it?
After a quick look, I'm pretty confident that we can also delete
rtw_p2p_get2() and rtw_p2p_set() unless I'm overlooking something.
Thanks,
Fabio M. De Francesco