On Tue, 2025-06-17 at 12:41 +0800, Edward Adam Davis wrote:
> According to ieee80211_s1g_optional_len(), it can be clearly seen that the
> maximum size of variable is 4 and it is an array. Based on the above, the
> parsing of the frame control field and optional field is optimized.
>
> Fixes: 1e1f706fc2ce ("wifi: cfg80211/mac80211: correctly parse S1G beacon optional elements")
> Reported-by: syzbot+6554b492c7008bcd3385@xxxxxxxxxxxxxxxxxxxxxxxxx
> Closes: https://syzkaller.appspot.com/bug?extid=6554b492c7008bcd3385
> Tested-by: syzbot+6554b492c7008bcd3385@xxxxxxxxxxxxxxxxxxxxxxxxx
> Signed-off-by: Edward Adam Davis <eadavis@xxxxxx>
> ---
> include/linux/ieee80211.h | 2 +-
> net/mac80211/mlme.c | 2 +-
> 2 files changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/include/linux/ieee80211.h b/include/linux/ieee80211.h
> index ce377f7fb912..556ce95e0b0f 100644
> --- a/include/linux/ieee80211.h
> +++ b/include/linux/ieee80211.h
> @@ -1278,7 +1278,7 @@ struct ieee80211_ext {
> u8 sa[ETH_ALEN];
> __le32 timestamp;
> u8 change_seq;
> - u8 variable[0];
> + u8 variable[4];
That's incorrect when those fields aren't present, and will result in
wrong sizeof(). I believe the correct fix is one I sent before, to just
make it []:
https://lore.kernel.org/linux-wireless/20250614003037.a3e82e882251.I2e8b58e56ff2a9f8b06c66f036578b7c1d4e4685@changeid/
johannes
