[PATCH] staging: rtl8723bs: validate monitor transmit frame lengths

[PATCH] staging: rtl8723bs: validate monitor transmit frame lengths

[Mariano Baragiola]

rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
then reads the 802.11 frame control field without checking that a base
802.11 header remains.

The data path also pulls the calculated 802.11, QoS and SNAP header
span before confirming that the skb contains it. A truncated frame can
therefore cause out-of-bounds reads or leave insufficient data for the
Ethernet address writes.

Reject frames that do not contain the base 802.11 header and data
frames that do not contain their complete calculated header span.

Signed-off-by: Mariano Baragiola <mbaragiola@linux.com>
---
 drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
index 6a97afd89dc7..bed8192ab44f 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
@@ -2033,6 +2033,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 
 	/* Skip the ratio tap header */
 	skb_pull(skb, rtap_len);
+	if (unlikely(skb->len < dot11_hdr_len))
+		goto fail;
 
 	dot11_hdr = (struct ieee80211_hdr *)skb->data;
 	frame_control = le16_to_cpu(dot11_hdr->frame_control);
@@ -2045,6 +2047,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 			qos_len = 2;
 		if ((frame_control & 0x0300) == 0x0300)
 			dot11_hdr_len += 6;
+		if (unlikely(skb->len < dot11_hdr_len + qos_len + snap_len))
+			goto fail;
 
 		memcpy(dst_mac_addr, dot11_hdr->addr1, sizeof(dst_mac_addr));
 		memcpy(src_mac_addr, dot11_hdr->addr2, sizeof(src_mac_addr));
-- 
2.55.0

Re: [PATCH] staging: rtl8723bs: validate monitor transmit frame lengths

[Dan Carpenter]

On Wed, Jul 15, 2026 at 07:59:38PM -0300, Mariano Baragiola wrote:
> rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
> then reads the 802.11 frame control field without checking that a base
> 802.11 header remains.
> 
> The data path also pulls the calculated 802.11, QoS and SNAP header
> span before confirming that the skb contains it. A truncated frame can
> therefore cause out-of-bounds reads or leave insufficient data for the
> Ethernet address writes.
> 
> Reject frames that do not contain the base 802.11 header and data
> frames that do not contain their complete calculated header span.
> 
> Signed-off-by: Mariano Baragiola <mbaragiola@linux.com>
> ---

Looks reasonable.  Please add a Fixes tag.

regards,
dan carpenter

[PATCH v2] staging: rtl8723bs: validate monitor transmit frame lengths

[Mariano Baragiola]

rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
then reads the 802.11 frame control field without checking that a base
802.11 header remains.

The data path also pulls the calculated 802.11, QoS and SNAP header
span before confirming that the skb contains it. A truncated frame can
therefore cause out-of-bounds reads or leave insufficient data for the
Ethernet address writes.

Reject frames that do not contain the base 802.11 header and data
frames that do not contain their complete calculated header span.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Mariano Baragiola <mbaragiola@linux.com>
---
 drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
index 6a97afd89dc7..bed8192ab44f 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
@@ -2033,6 +2033,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 
 	/* Skip the ratio tap header */
 	skb_pull(skb, rtap_len);
+	if (unlikely(skb->len < dot11_hdr_len))
+		goto fail;
 
 	dot11_hdr = (struct ieee80211_hdr *)skb->data;
 	frame_control = le16_to_cpu(dot11_hdr->frame_control);
@@ -2045,6 +2047,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 			qos_len = 2;
 		if ((frame_control & 0x0300) == 0x0300)
 			dot11_hdr_len += 6;
+		if (unlikely(skb->len < dot11_hdr_len + qos_len + snap_len))
+			goto fail;
 
 		memcpy(dst_mac_addr, dot11_hdr->addr1, sizeof(dst_mac_addr));
 		memcpy(src_mac_addr, dot11_hdr->addr2, sizeof(src_mac_addr));
-- 
2.55.0

Re: [PATCH v2] staging: rtl8723bs: validate monitor transmit frame lengths

[Greg Kroah-Hartman]

On Fri, Jul 17, 2026 at 10:03:56AM -0300, Mariano Baragiola wrote:
> rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
> then reads the 802.11 frame control field without checking that a base
> 802.11 header remains.
> 
> The data path also pulls the calculated 802.11, QoS and SNAP header
> span before confirming that the skb contains it. A truncated frame can
> therefore cause out-of-bounds reads or leave insufficient data for the
> Ethernet address writes.
> 
> Reject frames that do not contain the base 802.11 header and data
> frames that do not contain their complete calculated header span.
> 
> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
> Signed-off-by: Mariano Baragiola <mbaragiola@linux.com>
> ---
>  drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> index 6a97afd89dc7..bed8192ab44f 100644
> --- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> +++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
> @@ -2033,6 +2033,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
>  
>  	/* Skip the ratio tap header */
>  	skb_pull(skb, rtap_len);
> +	if (unlikely(skb->len < dot11_hdr_len))
> +		goto fail;
>  
>  	dot11_hdr = (struct ieee80211_hdr *)skb->data;
>  	frame_control = le16_to_cpu(dot11_hdr->frame_control);
> @@ -2045,6 +2047,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
>  			qos_len = 2;
>  		if ((frame_control & 0x0300) == 0x0300)
>  			dot11_hdr_len += 6;
> +		if (unlikely(skb->len < dot11_hdr_len + qos_len + snap_len))
> +			goto fail;
>  
>  		memcpy(dst_mac_addr, dot11_hdr->addr1, sizeof(dst_mac_addr));
>  		memcpy(src_mac_addr, dot11_hdr->addr2, sizeof(src_mac_addr));
> -- 
> 2.55.0
> 
> 

Hi,

This is the friendly patch-bot of Greg Kroah-Hartman.  You have sent him
a patch that has triggered this response.  He used to manually respond
to these common problems, but in order to save his sanity (he kept
writing the same thing over and over, yet to different people), I was
created.  Hopefully you will not take offence and will fix the problem
in your patch and resubmit it so that it can be accepted into the Linux
kernel tree.

You are receiving this message because of the following common error(s)
as indicated below:

- This looks like a new version of a previously submitted patch, but you
  did not list below the --- line any changes from the previous version.
  Please read the section entitled "The canonical patch format" in the
  kernel file, Documentation/process/submitting-patches.rst for what
  needs to be done here to properly describe this.

If you wish to discuss this problem further, or you have questions about
how to resolve this issue, please feel free to respond to this email and
Greg will reply once he has dug out from the pending patches received
from other developers.

thanks,

greg k-h's patch email bot

[PATCH v3] staging: rtl8723bs: validate monitor transmit frame lengths

[Mariano Baragiola]

rtw_cfg80211_monitor_if_xmit_entry() removes the radiotap header and
then reads the 802.11 frame control field without checking that a base
802.11 header remains.

The data path also pulls the calculated 802.11, QoS and SNAP header
span before confirming that the skb contains it. A truncated frame can
therefore cause out-of-bounds reads or leave insufficient data for the
Ethernet address writes.

Reject frames that do not contain the base 802.11 header and data
frames that do not contain their complete calculated header span.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
Signed-off-by: Mariano Baragiola <mbaragiola@linux.com>
---
Changes in v3:
- Add the below-separator changelog as requested by Greg K-H patch-bot.

Changes in v2:
- Add the Fixes tag as requested by Dan Carpenter.

 drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
index 6a97afd89dc7..bed8192ab44f 100644
--- a/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
+++ b/drivers/staging/rtl8723bs/os_dep/ioctl_cfg80211.c
@@ -2033,6 +2033,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 
 	/* Skip the ratio tap header */
 	skb_pull(skb, rtap_len);
+	if (unlikely(skb->len < dot11_hdr_len))
+		goto fail;
 
 	dot11_hdr = (struct ieee80211_hdr *)skb->data;
 	frame_control = le16_to_cpu(dot11_hdr->frame_control);
@@ -2045,6 +2047,8 @@ static netdev_tx_t rtw_cfg80211_monitor_if_xmit_entry(struct sk_buff *skb, struc
 			qos_len = 2;
 		if ((frame_control & 0x0300) == 0x0300)
 			dot11_hdr_len += 6;
+		if (unlikely(skb->len < dot11_hdr_len + qos_len + snap_len))
+			goto fail;
 
 		memcpy(dst_mac_addr, dot11_hdr->addr1, sizeof(dst_mac_addr));
 		memcpy(src_mac_addr, dot11_hdr->addr2, sizeof(src_mac_addr));
-- 
2.55.0