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wifi: mac80211: skip unused probe response countdown offsets

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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: af296bdb8d ("mac80211: move csa counters from sdata to beacon/presp")
Link: https://lore.kernel.org/all/20260708195911.84365-6-enderaoelyther@gmail.com/
Assisted-by: Codex:gpt-5
Assisted-by: Claude:opus-4.8
Signed-off-by: Zhao Li <enderaoelyther@gmail.com>
Link: https://patch.msgid.link/20260723011001.76851-1-enderaoelyther@gmail.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
This commit is contained in:
Zhao Li
2026-07-23 09:10:01 +08:00
committed by Johannes Berg
parent 0e4532ec65
commit fd2bf5e718
1 changed files with 2 additions and 1 deletions
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3
net/mac80211/tx.c
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@@ -5275,7 +5275,8 @@ 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;
}
}
}