[wireless] wifi: mac80211: fix mesh id corruption on 32 bit systems

Since the changed field size was increased to u64, mesh_bss_info_changed
pulls invalid bits from the first 3 bytes of the mesh id, clears them, and
passes them on to ieee80211_link_info_change_notify, because
ifmsh->mbss_changed was not updated to match its size.
Fix this by turning into ifmsh->mbss_changed into an unsigned long array with
64 bit size.

Fixes: 15ddba5f4311 ("wifi: mac80211: consistently use u64 for BSS changes")
Reported-by: Thomas Hühn <thomas.huehn@hs-nordhausen.de>
Signed-off-by: Felix Fietkau <nbd@nbd.name>
---
 net/mac80211/ieee80211_i.h | 2 +-
 net/mac80211/mesh.c        | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

> -----Original Message-----
> From: Felix Fietkau <nbd@nbd.name>
> Sent: Wednesday, September 13, 2023 1:02 PM
> To: linux-wireless@vger.kernel.org
> Cc: johannes@sipsolutions.net; pagadala.yesu.anjaneyulu@intel.com; Thomas Hühn
> <thomas.huehn@hs-nordhausen.de>
> Subject: [PATCH wireless] wifi: mac80211: fix mesh id corruption on 32 bit systems
> 
> Since the changed field size was increased to u64, mesh_bss_info_changed
> pulls invalid bits from the first 3 bytes of the mesh id, clears them, and
> passes them on to ieee80211_link_info_change_notify, because
> ifmsh->mbss_changed was not updated to match its size.
> Fix this by turning into ifmsh->mbss_changed into an unsigned long array with
> 64 bit size.
> 
> Fixes: 15ddba5f4311 ("wifi: mac80211: consistently use u64 for BSS changes")
> Reported-by: Thomas Hühn <thomas.huehn@hs-nordhausen.de>
> Signed-off-by: Felix Fietkau <nbd@nbd.name>
> ---
>  net/mac80211/ieee80211_i.h | 2 +-
>  net/mac80211/mesh.c        | 8 ++++----
>  2 files changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/net/mac80211/ieee80211_i.h b/net/mac80211/ieee80211_i.h
> index b8465d205076..3c5dbf95685d 100644
> --- a/net/mac80211/ieee80211_i.h
> +++ b/net/mac80211/ieee80211_i.h
> @@ -682,7 +682,7 @@ struct ieee80211_if_mesh {
>         struct timer_list mesh_path_root_timer;
> 
>         unsigned long wrkq_flags;
> -       unsigned long mbss_changed;
> +       unsigned long mbss_changed[64 / BITS_PER_LONG];

mbss_changed is a bitmap, so

DECLARE_BITMAP(mbss_changed, 64);

> 
>         bool userspace_handles_dfs;
> 
> diff --git a/net/mac80211/mesh.c b/net/mac80211/mesh.c
> index 0d0fbae51b61..092a1dc7314d 100644
> --- a/net/mac80211/mesh.c
> +++ b/net/mac80211/mesh.c
> @@ -1175,7 +1175,7 @@ void ieee80211_mbss_info_change_notify(struct ieee80211_sub_if_data *sdata,
> 
>         /* if we race with running work, worst case this work becomes a noop */
>         for_each_set_bit(bit, &bits, sizeof(changed) * BITS_PER_BYTE)
> -               set_bit(bit, &ifmsh->mbss_changed);
> +               set_bit(bit, ifmsh->mbss_changed);
>         set_bit(MESH_WORK_MBSS_CHANGED, &ifmsh->wrkq_flags);
>         wiphy_work_queue(sdata->local->hw.wiphy, &sdata->work);
>  }
> @@ -1257,7 +1257,7 @@ void ieee80211_stop_mesh(struct ieee80211_sub_if_data *sdata)
> 
>         /* clear any mesh work (for next join) we may have accrued */
>         ifmsh->wrkq_flags = 0;
> -       ifmsh->mbss_changed = 0;
> +       memset(ifmsh->mbss_changed, 0, sizeof(ifmsh->mbss_changed));

bitmap_zero(ifmsh->mbss_changed, 64);

bitmap_zero() can choose just '=0' or memset(0) according to BITS_PER_LONG. 

> 
>         local->fif_other_bss--;
>         atomic_dec(&local->iff_allmultis);
> @@ -1722,9 +1722,9 @@ static void mesh_bss_info_changed(struct ieee80211_sub_if_data *sdata)
>         u32 bit;
>         u64 changed = 0;
> 
> -       for_each_set_bit(bit, &ifmsh->mbss_changed,
> +       for_each_set_bit(bit, ifmsh->mbss_changed,
>                          sizeof(changed) * BITS_PER_BYTE) {
> -               clear_bit(bit, &ifmsh->mbss_changed);
> +               clear_bit(bit, ifmsh->mbss_changed);
>                 changed |= BIT(bit);
>         }
> 
> --
> 2.41.0