Re: [PATCH] net: mac80211: cfg: Initialize cnt before accessing elem

[Gustavo A. R. Silva]

On 23/11/24 11:08, Haoyu Li wrote:

With the new __counted_by annocation in cfg80211_rnr_elems, the "cnt"
struct member must be set before accessing the "elem" array. Failing to
do so will trigger a runtime warning when enabling CONFIG_UBSAN_BOUNDS
and CONFIG_FORTIFY_SOURCE.

Nice catch. :)

Fixes: 7b6d7087031b ("wifi: cfg80211: Annotate struct cfg80211_rnr_elems with 
__counted_by")

This should be Cc'd to stable:

Cc: sta...@vger.kernel.org

Signed-off-by: Haoyu Li <lihaoyu...@gmail.com>

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

Thanks
-Gustavo

---
  net/mac80211/cfg.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/mac80211/cfg.c b/net/mac80211/cfg.c
index 61a824ec33da..6936b1303e81 100644
--- a/net/mac80211/cfg.c
+++ b/net/mac80211/cfg.c
@@ -1105,13 +1105,13 @@ ieee80211_copy_rnr_beacon(u8 *pos, struct 
cfg80211_rnr_elems *dst,
  {
        int i, offset = 0;

+ dst->cnt = src->cnt;

        for (i = 0; i < src->cnt; i++) {
                memcpy(pos + offset, src->elem[i].data, src->elem[i].len);
                dst->elem[i].len = src->elem[i].len;
                dst->elem[i].data = pos + offset;
                offset += dst->elem[i].len;
        }
-       dst->cnt = src->cnt;

return offset;

  }