staging: rtl8723bs: fix potential out-of-bounds read in rtw_restruct_wmm_ie

From: Luka Gejak <[email protected]>

Separated OOB bug fix and cleanups to 2 series per Greg's request. No logical changes.

Luka Gejak (1):
staging: rtl8723bs: fix potential out-of-bounds read in
rtw_restruct_wmm_ie

 drivers/staging/rtl8723bs/core/rtw_mlme.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

2.53.0

From: Luka Gejak <[email protected]>

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.

---
 drivers/staging/rtl8723bs/core/rtw_mlme.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

index 22dc36e8e38a..2bd6f5367bdc 100644
@@ -1988,7 +1988,10 @@ 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++;

2.53.0

This really should have a note here which says:

v4: Sent this patch previously as part of a patchset, but pulled it
out by itself because it's a bugfix and the rest of the patchset was cleanups.

Otherwise, it's like I remember that I have seen something like this before but I don't know why I'm seeing this now. I thought maybe it was the same bug in a different driver or something so I had to look it up on lore.

Anyway, looks good otherwise.

regards,
dan carpenter