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staging: ks7010: use strscpy() to instead of strncpy()

PATCH In review [email protected] 2 participants 5 messages Dec 26, 2022 – Dec 29, 2022 Staging

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#0 lore raw

PATCH 1/1 staging: ks7010: use strscpy() to instead of strncpy()

From: Xu Panda <[email protected]>

The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL-terminated strings.

Signed-off-by Xu Panda <[email protected]>
Signed-off-by Yang Yang <[email protected]>
---
 drivers/staging/ks7010/ks_wlan_net.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/staging/ks7010/ks_wlan_net.c +1 -2
index 044c807ca022..e03c87f0bfe7 100644
@@ -382,8 +382,7 @@ static int ks_wlan_get_nick(struct net_device *dev,
 		return -EPERM;
 
 	/* for SLEEP MODE */
-	strncpy(extra, priv->nick, 16);
-	extra[16] = '\0';
+	strscpy(extra, priv->nick, 17);
 	dwrq->data.length = strlen(extra) + 1;
 
 	return 0;
Signature · 1 line
2.15.2
#1 lore raw
Quoted 16 lines · On Mon, Dec 26, 2022 at 07:03:24PM +0800, [email protected] wrote:

From: Xu Panda <[email protected]>

The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL-terminated strings.

Signed-off-by Xu Panda <[email protected]>
Signed-off-by Yang Yang <[email protected]>
---
 drivers/staging/ks7010/ks_wlan_net.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/staging/ks7010/ks_wlan_net.c +0 -0
index 044c807ca022..e03c87f0bfe7 100644

drivers/staging/ks7010/ks_wlan_net.c static int ks_wlan_get_nick(struct net_device *dev, · line 385

Quoted 6 lines
drivers/staging/ks7010/ks_wlan_net.c +1 -2
@@ -382,8 +382,7 @@ static int ks_wlan_get_nick(struct net_device *dev,
 		return -EPERM;
 
 	/* for SLEEP MODE */
-	strncpy(extra, priv->nick, 16);
-	extra[16] = '\0';
+	strscpy(extra, priv->nick, 17);

I think this code is a buffer overflow. This is an implementation of SIOCGIWNICKN.

net/wireless/wext-core.c
169 [IW_IOCTL_IDX(SIOCGIWNICKN)] = {

   170                  .header_type    = IW_HEADER_TYPE_POINT,
   171                  .token_size     = 1,
   172                  .max_tokens     = IW_ESSID_MAX_SIZE,

173 },

As you can see there is a .max_tokens but no .min_tokens. It is called from ioctl_standard_iw_point(). So if the user specifies something smaller than 17 it leads to a buffer overflow.

Your patch is mechanically correct, but now that we have eyes on the code we should fix the security bug instead making checkpatch happy or whatever.

regards,
dan carpenter

#2 lore raw
Quoted 19 lines · Dan Carpenter
Quoted 18 lines · On Mon, Dec 26, 2022 at 07:03:24PM +0800, [email protected] wrote:

From: Xu Panda <[email protected]>

The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL-terminated strings.

Signed-off-by Xu Panda <[email protected]>
Signed-off-by Yang Yang <[email protected]>
---
 drivers/staging/ks7010/ks_wlan_net.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/staging/ks7010/ks_wlan_net.c +0 -0
index 044c807ca022..e03c87f0bfe7 100644
@@ -382,8 +382,7 @@ static int ks_wlan_get_nick(struct net_device *dev,
 		return -EPERM;
Quoted 7 lines

drivers/staging/ks7010/ks_wlan_net.c static int ks_wlan_get_nick(struct net_device *dev, · line 385

Quoted 4 lines
drivers/staging/ks7010/ks_wlan_net.c +1 -2
 	/* for SLEEP MODE */
-	strncpy(extra, priv->nick, 16);
-	extra[16] = '\0';
+	strscpy(extra, priv->nick, 17);

I think this code is a buffer overflow. This is an implementation of SIOCGIWNICKN.

Huh... Maybe I'm wrong. I looked at a couple other implementations of SIOCGIWNICKN and they all seem to assume a 17 character buffer...

Let me look deeper. I guess for now assume I am wrong.

regards,
dan carpenter

Reviewed-by
#3 lore raw
In reply to Dan Carpenter
Quoted 27 lines · Dan Carpenter
Quoted 16 lines · On Mon, Dec 26, 2022 at 07:03:24PM +0800, [email protected] wrote:

From: Xu Panda <[email protected]>

The implementation of strscpy() is more robust and safer. That's now the recommended way to copy NUL-terminated strings.

Signed-off-by Xu Panda <[email protected]>
Signed-off-by Yang Yang <[email protected]>
---
 drivers/staging/ks7010/ks_wlan_net.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)
drivers/staging/ks7010/ks_wlan_net.c +0 -0
index 044c807ca022..e03c87f0bfe7 100644

drivers/staging/ks7010/ks_wlan_net.c static int ks_wlan_get_nick(struct net_device *dev, · line 385

Quoted 6 lines
drivers/staging/ks7010/ks_wlan_net.c +1 -2
@@ -382,8 +382,7 @@ static int ks_wlan_get_nick(struct net_device *dev,
 		return -EPERM;
 
 	/* for SLEEP MODE */
-	strncpy(extra, priv->nick, 16);
-	extra[16] = '\0';
+	strscpy(extra, priv->nick, 17);

I think this code is a buffer overflow. This is an implementation of SIOCGIWNICKN.

Quoted 7 lines

net/wireless/wext-core.c
169 [IW_IOCTL_IDX(SIOCGIWNICKN)] = {

   170                  .header_type    = IW_HEADER_TYPE_POINT,
   171                  .token_size     = 1,
   172                  .max_tokens     = IW_ESSID_MAX_SIZE,

173 },

Yeah. I was wrong. The extra size here is .max_tokens * .token_size so it's 32.

Sorry for the noise!

Reviewed-by Dan Carpenter <[email protected]>

regards,
dan carpenter