2022-04-04 11:32:36

by Charlie Sands

Subject: [PATCH] staging: r8188eu: Fix unsafe memory access by memcmp.

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]>
---
drivers/staging/r8188eu/os_dep/ioctl_linux.c | 20 ++++++++++++--------
1 file changed, 12 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..1cfac1b27eb7 100644
--- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
+++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
@@ -3233,23 +3233,27 @@ 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_ptr[9];
+ if (copy_from_user(wrqu_data_ptr, wrqu->data.pointer, 9))
+ return 0;
+
+ if (!memcmp(wrqu_data_ptr, "status", 6)) {
rtw_p2p_get_status(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "role", 4)) {
+ } else if (!memcmp(wrqu_data_ptr, "role", 4)) {
rtw_p2p_get_role(dev, info, wrqu, extra);
- } else if (!memcmp(wrqu->data.pointer, "peer_ifa", 8)) {
+ } else if (!memcmp(wrqu_data_ptr, "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_ptr, "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_ptr, "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_ptr, "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_ptr, "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_ptr, "op_ch", 5)) {
rtw_p2p_get_op_ch(dev, info, wrqu, extra);
}
return 0;
--
2.35.1

2022-04-05 01:02:56

by Pavel Skripkin

Subject: Re: [PATCH] staging: r8188eu: Fix unsafe memory access by memcmp.

Hi Charlie,

On 4/1/22 23:12, 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]>
> ---
> drivers/staging/r8188eu/os_dep/ioctl_linux.c | 20 ++++++++++++--------
> 1 file changed, 12 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..1cfac1b27eb7 100644
> --- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> +++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> @@ -3233,23 +3233,27 @@ 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_ptr[9];
> + if (copy_from_user(wrqu_data_ptr, wrqu->data.pointer, 9))
> + return 0;

-EFAULT is standard return value in case of `copy_{to_from}_user` failure



With regards,
Pavel Skripkin

2022-04-05 01:06:35

by Greg Kroah-Hartman

Subject: Re: [PATCH] staging: r8188eu: Fix unsafe memory access by memcmp.

On Fri, Apr 01, 2022 at 04:12:47PM -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]>
> ---
> drivers/staging/r8188eu/os_dep/ioctl_linux.c | 20 ++++++++++++--------
> 1 file changed, 12 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..1cfac1b27eb7 100644
> --- a/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> +++ b/drivers/staging/r8188eu/os_dep/ioctl_linux.c
> @@ -3233,23 +3233,27 @@ 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_ptr[9];
> + if (copy_from_user(wrqu_data_ptr, wrqu->data.pointer, 9))
> + return 0;

Please do not add checkpatch issues when trying to fix up other issues
:(

And that's a very odd variable name you are creating. That is not a
pointer at all, and either way, it should not be part of a variable
name, this isn't Windows code :)

thanks,

greg k-h