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;
+
+ if (!memcmp(wrqu_data, "status", 6)) {
rtw_p2p_get_status(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "role", 4)) {
+ } else if (!memcmp(wrqu_data, "role", 4)) {
rtw_p2p_get_role(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "peer_ifa", 8)) {
+ } else if (!memcmp(wrqu_data, "peer_ifa", 8)) {
rtw_p2p_get_peer_ifaddr(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "req_cm", 6)) {
+ } else if (!memcmp(wrqu_data, "req_cm", 6)) {
rtw_p2p_get_req_cm(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "peer_deva", 9)) {
+ } else if (!memcmp(wrqu_data, "peer_deva", 9)) {
/* Get the P2P device address when receiving the provision discovery request frame. */
rtw_p2p_get_peer_devaddr(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "group_id", 8)) {
+ } else if (!memcmp(wrqu_data, "group_id", 8)) {
rtw_p2p_get_groupid(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "peer_deva_inv", 9)) {
+ } else if (!memcmp(wrqu_data, "peer_deva_inv", 9)) {
/* Get the P2P device address when receiving the P2P Invitation request frame. */
rtw_p2p_get_peer_devaddr_by_invitation(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "op_ch", 5)) {
+ } else if (!memcmp(wrqu_data, "op_ch", 5)) {
rtw_p2p_get_op_ch(dev, info, wrqu, extra);
}
return 0;
--
2.35.1
On 4/4/22 04:52, 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(-)
>
Hi Charlie,
thanks for your patch. Looks good to me, but you should include
staging: r8188eu: in the subject line.
"staging: r8188eu: Fix unsafe memory access by memcmp"
thanks,
Michael
On Mon, Apr 04, 2022 at 04:29:48PM +0200, Fabio M. De Francesco wrote:
> On luned? 4 aprile 2022 14:03:32 CEST Dan Carpenter wrote:
> > On Mon, Apr 04, 2022 at 01:25:37PM +0200, Fabio M. De Francesco wrote:
> > > 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.
> >
> > What are the problems with rtw_p2p_get2() and rtw_p2p_set()?
> >
> > regards,
> > dan carpenter
> >
> Is it safe to access user space pointers without using proper helpers?
No.