Re: [PATCH v2] wifi: brcmfmac: Replace 1-element arrays with flexible arrays

Gustavo A. R. Silva
2023-09-14T17:18:53Z

On 9/14/23 01:02, Juerg Haefliger wrote:
> Since commit 2d47c6956ab3 ("ubsan: Tighten UBSAN_BOUNDS on GCC"),
> UBSAN_BOUNDS no longer pretends 1-element arrays are unbounded. Walking
> 'element' and 'channel_list' will trigger warnings, so make them proper
> flexible arrays.
>
> False positive warnings were:
>
> UBSAN: array-index-out-of-bounds in drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:6984:20
> index 1 is out of range for type '__le32 [1]'
>
> UBSAN: array-index-out-of-bounds in drivers/net/wireless/broadcom/brcm80211/brcmfmac/cfg80211.c:1126:27
> index 1 is out of range for type '__le16 [1]'
>
> for these lines of code:
>
> 6884 ch.chspec = (u16)le32_to_cpu(list->element[i]);
>
> 1126 params_le->channel_list[i] = cpu_to_le16(chanspec);
>
> Cc: stable@vger.kernel.org # 6.5+
> Signed-off-by: Juerg Haefliger <juerg.haefliger@canonical.com>

Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>

Thanks
--
Gustavo

>
> ---
> v2:
> - Use element[] instead of DFA() in brcmf_chanspec_list.
> - Add Cc: stable tag
> ---
> .../wireless/broadcom/brcm80211/brcmfmac/fwil_types.h | 9 +++++++--
> 1 file changed, 7 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
> index bece26741d3a..611d1a6aabb9 100644
> --- a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
> +++ b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
> @@ -442,7 +442,12 @@ struct brcmf_scan_params_v2_le {
> * fixed parameter portion is assumed, otherwise
> * ssid in the fixed portion is ignored
> */
> - __le16 channel_list[1]; /* list of chanspecs */
> + union {
> + __le16 padding; /* Reserve space for at least 1 entry for abort
> + * which uses an on stack brcmf_scan_params_v2_le
> + */
> + DECLARE_FLEX_ARRAY(__le16, channel_list); /* chanspecs */
> + };
> };
>
> struct brcmf_scan_results {
> @@ -702,7 +707,7 @@ struct brcmf_sta_info_le {
>
> struct brcmf_chanspec_list {
> __le32 count; /* # of entries */
> - __le32 element[1]; /* variable length uint32 list */
> + __le32 element[]; /* variable length uint32 list */
> };
>
> /*