Re: [PATCH v2] staging: rtl8723bs: fix missing frame length checks in OnAuthClient

Luka Gejak
2026-04-15T04:47:55Z

On Tue Apr 14, 2026 at 11:39 PM CEST, Alexandru Hossu wrote:
> OnAuthClient() accesses pframe without first verifying that pkt_len is
> large enough to contain a valid 802.11 management frame header:
>
> - get_da(pframe) reads bytes 4-9, requiring pkt_len >= 10
> - GetPrivacy(pframe) reads the FC field at bytes 0-1
>
> Additionally, when pkt_len < WLAN_HDR_A3_LEN + _AUTH_IE_OFFSET_ the
> unsigned subtraction passed to rtw_get_ie() wraps around, causing it
> to scan well past the end of the buffer.
>
> Add an early check against WLAN_HDR_A3_LEN before any pframe access,
> and a second check against WLAN_HDR_A3_LEN + offset + 6 after computing
> offset to guard the seq/status reads and the rtw_get_ie() call.
>
> Suggested-by: Dan Carpenter <error27@gmail.com>
> Fixes: 554c0a3abf21 ("staging: Add rtl8723bs sdio wifi driver")
> Cc: stable@vger.kernel.org
> Signed-off-by: Alexandru Hossu <hossu.alexandru@gmail.com>
> ---
> Changes in v2:
> - Replace incorrect Reported-by tag with Suggested-by: Dan spotted the
> missing length check during code review of the heap overflow fix; he
> did not file a separate bug report
> - Add missing version changelog (the initial submission was incorrectly
> labeled v2; no v1 was ever sent to the list)
>
> drivers/staging/rtl8723bs/core/rtw_mlme_ext.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> index 90f27665667a..884cd39ec756 100644
> --- a/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> +++ b/drivers/staging/rtl8723bs/core/rtw_mlme_ext.c
> @@ -860,6 +860,9 @@ unsigned int OnAuthClient(struct adapter *padapter, union recv_frame *precv_fram
> u8 *pframe = precv_frame->u.hdr.rx_data;
> uint pkt_len = precv_frame->u.hdr.len;
>
> + if (pkt_len < WLAN_HDR_A3_LEN)
> + goto authclnt_fail;
> +
> /* check A1 matches or not */
> if (memcmp(myid(&(padapter->eeprompriv)), get_da(pframe), ETH_ALEN))
> return _SUCCESS;
> @@ -869,6 +872,9 @@ unsigned int OnAuthClient(struct adapter *padapter, union recv_frame *precv_fram
>
> offset = (GetPrivacy(pframe)) ? 4 : 0;
>
> + if (pkt_len < WLAN_HDR_A3_LEN + offset + 6)
> + goto authclnt_fail;
> +
> seq = le16_to_cpu(*(__le16 *)((SIZE_PTR)pframe + WLAN_HDR_A3_LEN + offset + 2));
> status = le16_to_cpu(*(__le16 *)((SIZE_PTR)pframe + WLAN_HDR_A3_LEN + offset + 4));
>

LGTM.
Reviewed-by: Luka Gejak <luka.gejak@linux.dev>
Best regards,
Luka Gejak