Re: [PATCH] wifi: mwifiex: bound the pairwise-cipher OUI walk to the IE length

[Francesco Dolcini]

On Sat, Jul 11, 2026 at 09:13:34AM +0200, Doruk Tan Ozturk wrote:
> mwifiex_search_oui_in_ie() reads the pairwise-cipher (PTK) count from a
> beacon/probe-response RSN or WPA information element:
> 
> 	count = iebody->ptk_cnt[0];
> 
> and then walks "count" 4-byte OUIs from the element, comparing each with
> memcmp(). The count byte comes straight from the (attacker-supplied) IE
> and is never checked against the element's own length. The callers admit
> the element on element_id alone (has_ieee_hdr() / has_vendor_hdr(), no
> length check), so a crafted RSN/WPA IE with a large pairwise count makes
> the walk read up to 255 * 4 bytes past the element -- an out-of-bounds
> read of the kmemdup()'d beacon buffer, reachable from any AP whose
> beacon/probe response is processed during scan result parsing.
> 
> Pass the number of available IE bytes to the walk and reject a count
> whose OUI list would not fit, keeping the loop within the element.
> 
> Found by 0sec (https://0sec.ai) using automated source analysis; the
> unbounded count-driven walk is evident from source. Compile-tested.
> 
> Fixes: 5e6e3a92b9a4 ("wireless: mwifiex: initial commit for Marvell mwifiex driver")
> Cc: stable@xxxxxxxxxxxxxxx
> Assisted-by: 0sec:claude-opus-4-8
> Signed-off-by: Doruk Tan Ozturk <doruk@xxxxxxx>
> ---
>  drivers/net/wireless/marvell/mwifiex/scan.c | 22 ++++++++++++++++++---
>  1 file changed, 19 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/net/wireless/marvell/mwifiex/scan.c b/drivers/net/wireless/marvell/mwifiex/scan.c
> index 97c0ec3b822e..3a55fc6f1b54 100644
> --- a/drivers/net/wireless/marvell/mwifiex/scan.c
> +++ b/drivers/net/wireless/marvell/mwifiex/scan.c
> @@ -104,12 +104,21 @@ has_vendor_hdr(struct ieee_types_vendor_specific *ie, u8 key)
>   * a given oui in PTK.
>   */
>  static u8
> -mwifiex_search_oui_in_ie(struct ie_body *iebody, u8 *oui)
> +mwifiex_search_oui_in_ie(struct ie_body *iebody, u8 *oui, int ie_len)
>  {
>  	u8 count;
>  
> +	/* Need grp_key_oui[4] + ptk_cnt[2] before reading the OUI count. */
> +	if (ie_len < (int)offsetof(struct ie_body, ptk_body))

maybe define an intermediate variable to store `offsetof(struct ie_body, ptk_body)`
so that it is clear what this is, and you also can re-use it later?

Francesco