Messages in this thread | | | Date | Tue, 24 Oct 2023 20:37:31 -0600 | Subject | Re: [RFC - is this a bug?] wifi: ath10k: Asking for some light on this, please :) | From | "Gustavo A. R. Silva" <> |
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On 10/24/23 14:49, Johannes Berg wrote: > On Tue, 2023-10-24 at 14:41 -0600, Gustavo A. R. Silva wrote: >> >> It seems we run into the same issue in the function below, even in the >> case this `memset()` is unnecessary (which it seems it's not): >> >> 8920 memset(skb->data, 0, sizeof(*cmd)); >> >> Notice that if `cap->peer_chan_len == 0` or `cap->peer_chan_len == 1`, >> in the original code, we have `len == sizeof(*cmd) == 128`: > > Right. > >> - /* tdls peer update cmd has place holder for one channel*/ >> - chan_len = cap->peer_chan_len ? (cap->peer_chan_len - 1) : 0; >> - >> - len = sizeof(*cmd) + chan_len * sizeof(*chan); >> + len = struct_size(cmd, peer_capab.peer_chan_list, cap->peer_chan_len); >> >> skb = ath10k_wmi_alloc_skb(ar, len); >> if (!skb) >> >> which makes `round_len == roundup(len, 4) == struct_size(cmd,...,...) == 104` >> when `cap->peer_chan_len == 0` > > And yeah, that's really the issue, it only matters for ==0. For a moment > there I thought that doesn't even make sense, but it looks like it never > even becomes non-zero. > > No idea then, sorry. You'd hope firmware doesn't care about the actual > message size if the inner data says "0 entries", but who knows? And how > many firmware versions are there? :) > > So I guess you'd want to stay compatible, even if it means having a > > chan_len = min(cap->peer_chan_len, 1); > > for the struct_size()?
Yeah, that's an alternative.
I'll wait for the maintainers to chime in and see if they have a different opinion.
Thanks -- Gustavo
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