[PATCH] staging: rtl8723bs: fix integer underflow in TKIP MIC verification

[PATCH] staging: rtl8723bs: fix integer underflow in TKIP MIC verification

[Delene Tchio Romuald]

In recvframe_chkmic(), datalen is computed as:

  datalen = len - hdrlen - iv_len - icv_len - 8;

All operands are unsigned, so if the frame is shorter than the sum of
header, IV, ICV, and MIC lengths, the subtraction wraps to a very
large value. This corrupted datalen is then passed to
rtw_seccalctkipmic() and used as a pointer offset, leading to
out-of-bounds reads on kernel heap memory.

Add a minimum frame length check before the subtraction to prevent
the unsigned integer underflow.

Cc: stable@vger.kernel.org
Signed-off-by: Delene Tchio Romuald <delenetchior1@gmail.com>
---
 drivers/staging/rtl8723bs/core/rtw_recv.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/staging/rtl8723bs/core/rtw_recv.c b/drivers/staging/rtl8723bs/core/rtw_recv.c
index 337671b12..8d3c6761a 100644
--- a/drivers/staging/rtl8723bs/core/rtw_recv.c
+++ b/drivers/staging/rtl8723bs/core/rtw_recv.c
@@ -390,6 +390,13 @@ static signed int recvframe_chkmic(struct adapter *adapter,  union recv_frame *p
 				mickey = &stainfo->dot11tkiprxmickey.skey[0];
 			}
 
+			/* Ensure the frame is large enough for TKIP MIC verification */
+			if (precvframe->u.hdr.len <= prxattrib->hdrlen +
+			    prxattrib->iv_len + prxattrib->icv_len + 8) {
+				res = _FAIL;
+				goto exit;
+			}
+
 			datalen = precvframe->u.hdr.len-prxattrib->hdrlen-prxattrib->iv_len-prxattrib->icv_len-8;/* icv_len included the mic code */
 			pframe = precvframe->u.hdr.rx_data;
 			payload = pframe+prxattrib->hdrlen+prxattrib->iv_len;
-- 
2.43.0

Re: [PATCH] staging: rtl8723bs: fix integer underflow in TKIP MIC verification

[Ethan Tidmore]

On Sat Apr 4, 2026 at 5:57 PM CDT, Delene Tchio Romuald wrote:
> In recvframe_chkmic(), datalen is computed as:
>
>   datalen = len - hdrlen - iv_len - icv_len - 8;
>
> All operands are unsigned, so if the frame is shorter than the sum of
> header, IV, ICV, and MIC lengths, the subtraction wraps to a very
> large value. This corrupted datalen is then passed to
> rtw_seccalctkipmic() and used as a pointer offset, leading to
> out-of-bounds reads on kernel heap memory.
>
> Add a minimum frame length check before the subtraction to prevent
> the unsigned integer underflow.
>
> Cc: stable@vger.kernel.org
> Signed-off-by: Delene Tchio Romuald <delenetchior1@gmail.com>
> ---

Doesn't apply to staging-next.

Thanks,

ET

[PATCH v2] staging: rtl8723bs: fix integer underflow in TKIP MIC verification

[Delene Tchio Romuald]

In recvframe_chkmic(), datalen is computed as:

  datalen = len - hdrlen - iv_len - icv_len - 8;

All operands are unsigned, so if the frame is shorter than the sum of
header, IV, ICV, and MIC lengths, the subtraction wraps to a very
large value. This corrupted datalen is then passed to
rtw_seccalctkipmic() and used as a pointer offset, leading to
out-of-bounds reads on kernel heap memory.

Add a minimum frame length check before the subtraction to prevent
the unsigned integer underflow.

Cc: stable@vger.kernel.org
Signed-off-by: Delene Tchio Romuald <delenetchior1@gmail.com>
---
 drivers/staging/rtl8723bs/core/rtw_recv.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/staging/rtl8723bs/core/rtw_recv.c b/drivers/staging/rtl8723bs/core/rtw_recv.c
index f78194d50..1fc8bcf39 100644
--- a/drivers/staging/rtl8723bs/core/rtw_recv.c
+++ b/drivers/staging/rtl8723bs/core/rtw_recv.c
@@ -390,6 +390,13 @@ static signed int recvframe_chkmic(struct adapter *adapter,  union recv_frame *p
 				mickey = &stainfo->dot11tkiprxmickey.skey[0];
 			}
 
+			/* Ensure the frame is large enough for TKIP MIC verification */
+			if (precvframe->u.hdr.len <= prxattrib->hdrlen +
+			    prxattrib->iv_len + prxattrib->icv_len + 8) {
+				res = _FAIL;
+				goto exit;
+			}
+
 			datalen = precvframe->u.hdr.len - prxattrib->hdrlen - prxattrib->iv_len - prxattrib->icv_len - 8;/* icv_len included the mic code */
 			pframe = precvframe->u.hdr.rx_data;
 			payload = pframe + prxattrib->hdrlen + prxattrib->iv_len;
-- 
2.43.0

Re: [PATCH v2] staging: rtl8723bs: fix integer underflow in TKIP MIC verification

[Greg KH]

On Sun, Apr 05, 2026 at 12:55:22AM +0100, Delene Tchio Romuald wrote:
> In recvframe_chkmic(), datalen is computed as:
> 
>   datalen = len - hdrlen - iv_len - icv_len - 8;
> 
> All operands are unsigned, so if the frame is shorter than the sum of
> header, IV, ICV, and MIC lengths, the subtraction wraps to a very
> large value. This corrupted datalen is then passed to
> rtw_seccalctkipmic() and used as a pointer offset, leading to
> out-of-bounds reads on kernel heap memory.
> 
> Add a minimum frame length check before the subtraction to prevent
> the unsigned integer underflow.
> 
> Cc: stable@vger.kernel.org
> Signed-off-by: Delene Tchio Romuald <delenetchior1@gmail.com>
> ---
>  drivers/staging/rtl8723bs/core/rtw_recv.c | 7 +++++++
>  1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/staging/rtl8723bs/core/rtw_recv.c b/drivers/staging/rtl8723bs/core/rtw_recv.c
> index f78194d50..1fc8bcf39 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_recv.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_recv.c
> @@ -390,6 +390,13 @@ static signed int recvframe_chkmic(struct adapter *adapter,  union recv_frame *p
>  				mickey = &stainfo->dot11tkiprxmickey.skey[0];
>  			}
>  
> +			/* Ensure the frame is large enough for TKIP MIC verification */
> +			if (precvframe->u.hdr.len <= prxattrib->hdrlen +
> +			    prxattrib->iv_len + prxattrib->icv_len + 8) {
> +				res = _FAIL;
> +				goto exit;
> +			}
> +
>  			datalen = precvframe->u.hdr.len - prxattrib->hdrlen - prxattrib->iv_len - prxattrib->icv_len - 8;/* icv_len included the mic code */
>  			pframe = precvframe->u.hdr.rx_data;
>  			payload = pframe + prxattrib->hdrlen + prxattrib->iv_len;
> -- 
> 2.43.0
> 
> 

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
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If you wish to discuss this problem further, or you have questions about
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