wifi: brcmfmac: Replace 1-element arrays with flexible arrays

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: Kees Cook <keescook@chromium.org>
Reviewed-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230914070227.12028-1-juerg.haefliger@canonical.com

diff --git a/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h b/drivers/net/wireless/broadcom/brcm80211/brcmfmac/fwil_types.h
index bece267..611d1a6 100644 (file)
--- 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 */
 };
 
 /*