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

From: Gustavo A. R. Silva
Date: Mon Nov 25 2024 - 11:49:04 EST




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: stable@xxxxxxxxxxxxxxx

Signed-off-by: Haoyu Li <lihaoyu499@xxxxxxxxx>

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

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;
}