6.1-stable review patch. If anyone has any objections, please let me know.
------------------
From: Zhao Li <redacted>
[ Upstream commit fd2bf5e718108c00732eb07fd94a5d8830f62a9f ]
mac80211 copies cfg80211's variable-length countdown offset list into a
zero-initialized fixed-size array, leaving unused entries at zero. The
beacon branch already skips those zero entries, but the AP probe-response
branch writes through them unconditionally.
When a probe-response template has no countdown offset, the write through
an unused zero entry overwrites resp->data[0], corrupting the first byte of
the template. cfg80211 already bounds explicitly supplied non-zero offsets
in nl80211_parse_counter_offsets(), so this is a zero-sentinel bug, not an
out-of-bounds write.
Skip zero probe-response offsets, matching the beacon path.
Fixes: af296bdb8da4 ("mac80211: move csa counters from sdata to beacon/presp")
Link: https://lore.kernel.org/all/20260708195911.84365-6-enderaoelyther@gmail.com/ (local)
Assisted-by: Codex:gpt-5
Assisted-by: Claude:opus-4.8
Signed-off-by: Zhao Li <redacted>
Link: https://patch.msgid.link/20260723011001.76851-1-enderaoelyther@gmail.com (local)
Signed-off-by: Johannes Berg <redacted>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/mac80211/tx.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/net/mac80211/tx.c b/net/mac80211/tx.c
index 52fcb0c5f8fbe..31f000aa22309 100644
--- a/net/mac80211/tx.c
+++ b/net/mac80211/tx.c
@@ -4948,7 +4948,8 @@ static void ieee80211_set_beacon_cntdwn(struct ieee80211_sub_if_data *sdata,
if (sdata->vif.type == NL80211_IFTYPE_AP && resp) {
u16 *resp_offsets = resp->cntdwn_counter_offsets;
- resp->data[resp_offsets[i]] = count;
+ if (resp_offsets[i])
+ resp->data[resp_offsets[i]] = count;
}
}
}--
2.53.0