Kees Cook <keescook@xxxxxxxxxxxx> wrote:
> After commit e3eac9f32ec0 ("wifi: cfg80211: Annotate struct
> cfg80211_scan_request with __counted_by"), the compiler may enforce
> dynamic array indexing of req->channels to stay below n_channels. As a
> result, n_channels needs to be increased _before_ accessing the newly
> added array index. Increment it first, then use "i" for the prior index.
> Solves this warning in the coming GCC that has __counted_by support:
>
> ../drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c: In function 'brcmf_internal_escan_add_info':
> ../drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:3783:46: warning: operation on 'req->
> n_channels' may be undefined [-Wsequence-point]
> 3783 | req->channels[req->n_channels++] = chan;
> | ~~~~~~~~~~~~~~~^~
>
> Fixes: e3eac9f32ec0 ("wifi: cfg80211: Annotate struct cfg80211_scan_request with __counted_by")
> Cc: Arend van Spriel <aspriel@xxxxxxxxx>
> Cc: Franky Lin <franky.lin@xxxxxxxxxxxx>
> Cc: Hante Meuleman <hante.meuleman@xxxxxxxxxxxx>
> Cc: Kalle Valo <kvalo@xxxxxxxxxx>
> Cc: Chi-hsien Lin <chi-hsien.lin@xxxxxxxxxxxx>
> Cc: Ian Lin <ian.lin@xxxxxxxxxxxx>
> Cc: Johannes Berg <johannes.berg@xxxxxxxxx>
> Cc: Wright Feng <wright.feng@xxxxxxxxxxx>
> Cc: Hector Martin <marcan@xxxxxxxxx>
> Cc: linux-wireless@xxxxxxxxxxxxxxx
> Cc: brcm80211-dev-list.pdl@xxxxxxxxxxxx
> Signed-off-by: Kees Cook <keescook@xxxxxxxxxxxx>
> Reviewed-by: Hans de Goede <hdegoede@xxxxxxxxxx>
> Reviewed-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
> Reviewed-by: Gustavo A. R. Silva <gustavoars@xxxxxxxxxx>
I'm planning to queue this for wireless tree. Arend, ack?
--
https://patchwork.kernel.org/project/linux-wireless/patch/20240126223150.work.548-kees@xxxxxxxxxx/
https://wireless.wiki.kernel.org/en/developers/documentation/submittingpatches
