[PATCH v4 1/5] staging: rtl8723bs: fix potential out-of-bounds read in rtw_restruct_wmm_ie

[PATCH v4 1/5] staging: rtl8723bs: fix potential out-of-bounds read in rtw_restruct_wmm_ie

[Luka Gejak]

The current code checks 'i + 5 < in_len' at the end of
the if statement.
However, it accesses 'in_ie[i + 5]' before that check,
which can lead to an out-of-bounds read.

Move the length check to the beginning of the conditional
to ensure the index is within bounds before accessing the array.

Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")

Cc: stable@vger.kernel.org

Signed-off-by: Luka Gejak <lukagejak5@gmail.com>
---
 drivers/staging/rtl8723bs/core/rtw_mlme.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme.c b/drivers/staging/rtl8723bs/core/rtw_mlme.c
index 98704179ad35..7dfc2678924e 100644
--- a/drivers/staging/rtl8723bs/core/rtw_mlme.c
+++ b/drivers/staging/rtl8723bs/core/rtw_mlme.c
@@ -2000,7 +2000,10 @@ int rtw_restruct_wmm_ie(struct adapter *adapter, u8 *in_ie, u8 *out_ie, uint in_
 	while (i < in_len) {
 		ielength = initial_out_len;
 
-		if (in_ie[i] == 0xDD && in_ie[i+2] == 0x00 && in_ie[i+3] == 0x50  && in_ie[i+4] == 0xF2 && in_ie[i+5] == 0x02 && i+5 < in_len) { /* WMM element ID and OUI */
+		if (i + 5 < in_len &&
+		    in_ie[i] == 0xDD && in_ie[i + 2] == 0x00 &&
+		    in_ie[i + 3] == 0x50 && in_ie[i + 4] == 0xF2 &&
+		    in_ie[i + 5] == 0x02) {
 			for (j = i; j < i + 9; j++) {
 				out_ie[ielength] = in_ie[j];
 				ielength++;
-- 
2.52.0

Re: [PATCH v4 1/5] staging: rtl8723bs: fix potential out-of-bounds read in rtw_restruct_wmm_ie

[Dan Carpenter]

Please, slow down.  Only resend a patchset once per day.

On Thu, Jan 29, 2026 at 07:15:37PM +0100, Luka Gejak wrote:
> The current code checks 'i + 5 < in_len' at the end of
> the if statement.
> However, it accesses 'in_ie[i + 5]' before that check,
> which can lead to an out-of-bounds read.

The line breaks are weird looking.  You're putting a new line between
sentences and a blank line between paragraphs.  Just put a blank line
between paragraphs and delete the extra newline.

The out of bounds read is most likely going to be harmless.  Hopefully,
it would be detected and trigger a warning from the UBSan type tools.
Also if you got really unlucky and in_ie[] was at the end of a page
then it could cause a crash.

This bug is still definitely worth fixing.

> 
> Move the length check to the beginning of the conditional
> to ensure the index is within bounds before accessing the array.
> 
> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
> 
> Cc: stable@vger.kernel.org
> 
> Signed-off-by: Luka Gejak <lukagejak5@gmail.com>

Delete the blank lines in the S-o-b block.

regards,
dan carpenter