Hi,
On Tue, 2024-04-09 at 14:50 +0800, Michael-CY Lee wrote:
> MLD STA finds MLD AP's partner links by BSSID from the scan results.
> However, if the scan results contain BSSs with same BSSID but different
> BSS information, the MLD STA might assign a wrong BSS to one of the MLD
> AP's partner links.
As a clarification, why/how do we get into the situation that the same
BSSIDs exists with the wrong SSID in the supplicant?
Did the AP change its SSID and we still have the old one in the cache?
If that is the case, then maybe what we should be doing is to verify
that the BSS parameter change count matches. If not, it makes sense to
reject the BSS for now, which should trigger an ML probe request to
update the information and the next attempt will work fine.
Benjamin
> This patch avoids the problem by using both BSSID and SSID to find the
> MLD AP's partner links.
>
> Signed-off-by: Michael-CY Lee <michael-cy.lee@xxxxxxxxxxxx>
> ---
> wpa_supplicant/bss.c | 9 +++++++--
> wpa_supplicant/sme.c | 14 ++++++++------
> 2 files changed, 15 insertions(+), 8 deletions(-)
>
> diff --git a/wpa_supplicant/bss.c b/wpa_supplicant/bss.c
> index 289035310..4b8a98adf 100644
> --- a/wpa_supplicant/bss.c
> +++ b/wpa_supplicant/bss.c
> @@ -1529,8 +1529,13 @@ wpa_bss_parse_ml_rnr_ap_info(struct
> wpa_supplicant *wpa_s,
> wpa_printf(MSG_DEBUG,
> "MLD: Reported link not part of
> MLD");
> } else if (!(BIT(link_id) & *seen)) {
> - struct wpa_bss *neigh_bss =
> - wpa_bss_get_bssid(wpa_s, pos + 1);
> + struct wpa_bss *neigh_bss;
> +
> + if (ssid)
> + neigh_bss = wpa_bss_get(wpa_s, pos +
> 1, ssid->ssid,
> + ssid-
> >ssid_len);
> + else
> + neigh_bss = wpa_bss_get_bssid(wpa_s,
> pos + 1);
>
> *seen |= BIT(link_id);
> wpa_printf(MSG_DEBUG, "MLD: mld ID=%u, link
> ID=%u",
> diff --git a/wpa_supplicant/sme.c b/wpa_supplicant/sme.c
> index f08184f98..0643774a5 100644
> --- a/wpa_supplicant/sme.c
> +++ b/wpa_supplicant/sme.c
> @@ -390,7 +390,8 @@ static void wpas_ml_handle_removed_links(struct
> wpa_supplicant *wpa_s,
>
> #ifdef CONFIG_TESTING_OPTIONS
> static struct wpa_bss * wpas_ml_connect_pref(struct wpa_supplicant
> *wpa_s,
> - struct wpa_bss *bss)
> + struct wpa_bss *bss,
> + struct wpa_ssid *ssid)
> {
> unsigned int low, high, i;
>
> @@ -456,7 +457,7 @@ found:
> MAC2STR(wpa_s->links[i].bssid));
>
> /* Get the BSS entry and do the switch */
> - bss = wpa_bss_get_bssid(wpa_s, wpa_s->links[i].bssid);
> + bss = wpa_bss_get(wpa_s, wpa_s->links[i].bssid, ssid->ssid,
> ssid->ssid_len);
> wpa_s->mlo_assoc_link_id = i;
>
> return bss;
> @@ -515,7 +516,7 @@ out:
>
>
> static void wpas_sme_set_mlo_links(struct wpa_supplicant *wpa_s,
> - struct wpa_bss *bss)
> + struct wpa_bss *bss, struct
> wpa_ssid *ssid)
> {
> u8 i;
>
> @@ -533,7 +534,8 @@ static void wpas_sme_set_mlo_links(struct
> wpa_supplicant *wpa_s,
> if (bss->mld_link_id == i)
> wpa_s->links[i].bss = bss;
> else
> - wpa_s->links[i].bss =
> wpa_bss_get_bssid(wpa_s, bssid);
> + wpa_s->links[i].bss = wpa_bss_get(wpa_s,
> bssid, ssid->ssid,
> + ssid-
> >ssid_len);
> }
> }
>
> @@ -576,10 +578,10 @@ static void sme_send_authentication(struct
> wpa_supplicant *wpa_s,
> NULL, ssid, NULL) &&
> bss->valid_links) {
> wpa_printf(MSG_DEBUG, "MLD: In authentication");
> - wpas_sme_set_mlo_links(wpa_s, bss);
> + wpas_sme_set_mlo_links(wpa_s, bss, ssid);
>
> #ifdef CONFIG_TESTING_OPTIONS
> - bss = wpas_ml_connect_pref(wpa_s, bss);
> + bss = wpas_ml_connect_pref(wpa_s, bss, ssid);
>
> if (wpa_s->conf->mld_force_single_link) {
> wpa_printf(MSG_DEBUG, "MLD: Force single
> link");
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