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: sta...@vger.kernel.org # 6.5+
Signed-off-by: Juerg Haefliger <juerg.haefli...@canonical.com>

Reviewed-by: Gustavo A. R. Silva <gustavo...@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 */
  };
/*

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