Re: [PATCH v2] staging: rtl8723bs: fix remote heap information disclosure in issue_assocreq

Luka Gejak
2026-04-15T10:55:55Z

On Wed Apr 15, 2026 at 10:58 AM CEST, Dan Carpenter wrote:
> On Wed, Apr 15, 2026 at 07:03:02AM +0200, luka.gejak@linux.dev wrote:
>> From: Luka Gejak <luka.gejak@linux.dev>
>>
>> When building an association request frame, the driver copies the
>> ht capability ie using the attacker-controlled pIE->length from the
>> ap's beacon. If the ap provides a length greater than the size of
>> struct HT_caps_element (26 bytes), it causes an out-of-bounds read
>> of the adjacent heap memory (HT_info and network structures).
>> This uninitialized or sensitive memory is then transmitted over the air,
>> resulting in a remote heap information disclosure.
>>
>> Fix this by clamping the length passed to rtw_set_ie() to the actual
>> size of struct HT_caps_element.
>>
>> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
>> Cc: stable@vger.kernel.org
>> Signed-off-by: Luka Gejak <luka.gejak@linux.dev>
>> ---
>> ---
>> Changes in v2:
>> - Refactored rtw_set_ie() alignment to follow "open parenthesis" style.
>> - Allowed the line length to exceed 100 characters for better readability as requested by Greg KH.
>>
>> drivers/staging/rtl8723bs/core/rtw_mlme_ext.c | 4 +++-
>> 1 file changed, 3 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
>> index 5f00fe282d1b..08e597bc0345 100644
>> --- a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
>> +++ b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
>> @@ -2954,7 +2954,9 @@ void issue_assocreq(struct adapter *padapter)
>> if (padapter->mlmepriv.htpriv.ht_option) {
>> if (!(is_ap_in_tkip(padapter))) {
>> memcpy(&(pmlmeinfo->HT_caps), pIE->data, sizeof(struct HT_caps_element));
>> - pframe = rtw_set_ie(pframe, WLAN_EID_HT_CAPABILITY, pIE->length, (u8 *)(&(pmlmeinfo->HT_caps)), &(pattrib->pktlen));
>> + pframe = rtw_set_ie(pframe, WLAN_EID_HT_CAPABILITY,
>> + min_t(uint, pIE->length, sizeof(struct HT_caps_element)),
>> + (u8 *)&pmlmeinfo->HT_caps, &pattrib->pktlen);
>
> You're being conservative and trying to work around the invalid
> pIE->length, but in the case where the original code corrupts memory,
> we're allow to just give up and return a failure.
>
> There are two other cases where we trust pIE->length in this function
> and those need to be fixed as well.
>
> regards,
> dan carpenter

Hi Dan,
should I keep my approach as is or just return failure. I will fix other
cases as well with whatever approach you consider correct.
Best regards,
Luka Gejak