* [PATCH V2] Fix unsafe memory access by memcmp
@ 2022-04-04 2:52 Charlie Sands
2022-04-04 8:02 ` Michael Straube
` (2 more replies)
0 siblings, 3 replies; 10+ messages in thread
From: Charlie Sands @ 2022-04-04 2:52 UTC (permalink / raw)
To: gregkh; +Cc: Larry.Finger, phil, linux-staging, linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
---
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
^ permalink raw reply related [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 2:52 [PATCH V2] Fix unsafe memory access by memcmp Charlie Sands
@ 2022-04-04 8:02 ` Michael Straube
2022-04-04 10:50 ` Dan Carpenter
2022-04-04 16:33 ` Pavel Skripkin
2 siblings, 0 replies; 10+ messages in thread
From: Michael Straube @ 2022-04-04 8:02 UTC (permalink / raw)
To: Charlie Sands, gregkh
Cc: Larry.Finger, phil, linux-staging, linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> ---
>
> 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 2:52 [PATCH V2] Fix unsafe memory access by memcmp Charlie Sands
2022-04-04 8:02 ` Michael Straube
@ 2022-04-04 10:50 ` Dan Carpenter
2022-04-04 11:25 ` Fabio M. De Francesco
2022-04-04 16:33 ` Pavel Skripkin
2 siblings, 1 reply; 10+ messages in thread
From: Dan Carpenter @ 2022-04-04 10:50 UTC (permalink / raw)
To: Charlie Sands
Cc: gregkh, Larry.Finger, phil, linux-staging, linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> ---
>
> 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 10:50 ` Dan Carpenter
@ 2022-04-04 11:25 ` Fabio M. De Francesco
2022-04-04 12:03 ` Dan Carpenter
0 siblings, 1 reply; 10+ messages in thread
From: Fabio M. De Francesco @ 2022-04-04 11:25 UTC (permalink / raw)
To: Charlie Sands, Dan Carpenter
Cc: gregkh, Larry.Finger, phil, linux-staging, linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> > ---
> >
> > 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 11:25 ` Fabio M. De Francesco
@ 2022-04-04 12:03 ` Dan Carpenter
2022-04-04 14:29 ` Fabio M. De Francesco
0 siblings, 1 reply; 10+ messages in thread
From: Dan Carpenter @ 2022-04-04 12:03 UTC (permalink / raw)
To: Fabio M. De Francesco
Cc: Charlie Sands, gregkh, Larry.Finger, phil, linux-staging,
linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> > > ---
> > >
> > > 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
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 12:03 ` Dan Carpenter
@ 2022-04-04 14:29 ` Fabio M. De Francesco
2022-04-04 14:35 ` Dan Carpenter
2022-04-04 14:36 ` Greg KH
0 siblings, 2 replies; 10+ messages in thread
From: Fabio M. De Francesco @ 2022-04-04 14:29 UTC (permalink / raw)
To: Dan Carpenter
Cc: Charlie Sands, gregkh, Larry.Finger, phil, linux-staging,
linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> > > > ---
> > > >
> > > > 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?
In those cases I mean: is it safe without using copy_from_user()?
As I said, perhaps I'm overlooking something. However my conclusions
follow by your own argument.
If I understand what you wrote, you asked to delete rtw_p2p_get()
because it looks like nobody "has ever tested or used this code".
rtw_p2p_get2() and rtw_p2p_set() use the same pattern of rtw_p2p_get()
when they access user space without using the proper helpers.
Therefore, I thought that, if you suggest to delete rtw_p2p_get(), why
not also rtw_p2p_set() and rtw_p2p_get2() that use the same unsafe
accesses?
What am I still missing?
Thanks,
Fabio M. De Francesco
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 14:29 ` Fabio M. De Francesco
@ 2022-04-04 14:35 ` Dan Carpenter
2022-04-04 14:47 ` Fabio M. De Francesco
2022-04-04 14:36 ` Greg KH
1 sibling, 1 reply; 10+ messages in thread
From: Dan Carpenter @ 2022-04-04 14:35 UTC (permalink / raw)
To: Fabio M. De Francesco
Cc: Charlie Sands, gregkh, Larry.Finger, phil, linux-staging,
linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> > > > > ---
> > > > >
> > > > > 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.
> In those cases I mean: is it safe without using copy_from_user()?
Correct. You need to use copy_from_user().
>
> As I said, perhaps I'm overlooking something. However my conclusions
> follow by your own argument.
>
> If I understand what you wrote, you asked to delete rtw_p2p_get()
> because it looks like nobody "has ever tested or used this code".
>
> rtw_p2p_get2() and rtw_p2p_set() use the same pattern of rtw_p2p_get()
> when they access user space without using the proper helpers.
Those functions use "extra" which is a kernel pointer. Which user
pointer do they use? Sparse doesn't detect it.
regards,
dan carpenter
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 14:29 ` Fabio M. De Francesco
2022-04-04 14:35 ` Dan Carpenter
@ 2022-04-04 14:36 ` Greg KH
1 sibling, 0 replies; 10+ messages in thread
From: Greg KH @ 2022-04-04 14:36 UTC (permalink / raw)
To: Fabio M. De Francesco
Cc: Dan Carpenter, Charlie Sands, Larry.Finger, phil, linux-staging,
linux-kernel, paskripkin
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 <sandsch@northvilleschools.net>
> > > > > ---
> > > > >
> > > > > 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.
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 14:35 ` Dan Carpenter
@ 2022-04-04 14:47 ` Fabio M. De Francesco
0 siblings, 0 replies; 10+ messages in thread
From: Fabio M. De Francesco @ 2022-04-04 14:47 UTC (permalink / raw)
To: Dan Carpenter
Cc: Charlie Sands, gregkh, Larry.Finger, phil, linux-staging,
linux-kernel, paskripkin
On luned? 4 aprile 2022 16:35:31 CEST Dan Carpenter wrote:
> On Mon, Apr 04, 2022 at 04:29:48PM +0200, Fabio M. De Francesco wrote:
> > Is it safe to access user space pointers without using proper helpers?
>
> No.
>
> > In those cases I mean: is it safe without using copy_from_user()?
>
> Correct. You need to use copy_from_user().
>
> >
> > As I said, perhaps I'm overlooking something. However my conclusions
> > follow by your own argument.
> >
> > If I understand what you wrote, you asked to delete rtw_p2p_get()
> > because it looks like nobody "has ever tested or used this code".
> >
> > rtw_p2p_get2() and rtw_p2p_set() use the same pattern of rtw_p2p_get()
> > when they access user space without using the proper helpers.
>
> Those functions use "extra" which is a kernel pointer. Which user
> pointer do they use? Sparse doesn't detect it.
You're right, sorry. This is what I had overlooked. I took a brief look
(just 5 seconds or something) and saw the same arguments that
rtw_p2p_get() takes and then a long list of calls to memcmp().
I overlooked that they were called using the 4th argument ("extra").
Sorry for the noise.
Fabio
^ permalink raw reply [flat|nested] 10+ messages in thread
* Re: [PATCH V2] Fix unsafe memory access by memcmp
2022-04-04 2:52 [PATCH V2] Fix unsafe memory access by memcmp Charlie Sands
2022-04-04 8:02 ` Michael Straube
2022-04-04 10:50 ` Dan Carpenter
@ 2022-04-04 16:33 ` Pavel Skripkin
2 siblings, 0 replies; 10+ messages in thread
From: Pavel Skripkin @ 2022-04-04 16:33 UTC (permalink / raw)
To: Charlie Sands, gregkh; +Cc: Larry.Finger, phil, linux-staging, linux-kernel
[-- Attachment #1.1: Type: text/plain, Size: 1414 bytes --]
Hi Charlie,
On 4/4/22 05:52, 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 <sandsch@northvilleschools.net>
> ---
>
> 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.
>
You did not improved error handling of copy_from_user() as I suggested.
if (expr) and if (expr != 0) are exactly the same
> 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;
> +
I've suggested to return -EFAULT here
With regards,
Pavel Skripkin
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^ permalink raw reply [flat|nested] 10+ messages in thread
end of thread, other threads:[~2022-04-04 16:33 UTC | newest]
Thread overview: 10+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-04-04 2:52 [PATCH V2] Fix unsafe memory access by memcmp Charlie Sands
2022-04-04 8:02 ` Michael Straube
2022-04-04 10:50 ` Dan Carpenter
2022-04-04 11:25 ` Fabio M. De Francesco
2022-04-04 12:03 ` Dan Carpenter
2022-04-04 14:29 ` Fabio M. De Francesco
2022-04-04 14:35 ` Dan Carpenter
2022-04-04 14:47 ` Fabio M. De Francesco
2022-04-04 14:36 ` Greg KH
2022-04-04 16:33 ` Pavel Skripkin
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