[PATCH 5.10 28/77] cfg80211: scan: fix RCU in cfg80211_add_nontrans_list()

Greg Kroah-Hartman
2021-11-01T09:34:43Z

From: Johannes Berg <johannes.berg@intel.com>

commit a2083eeb119fb9307258baea9b7c243ca9a2e0b6 upstream.

The SSID pointer is pointing to RCU protected data, so we
need to have it under rcu_read_lock() for the entire use.
Fix this.

Cc: stable@vger.kernel.org
Fixes: 0b8fb8235be8 ("cfg80211: Parsing of Multiple BSSID information in scanning")
Link: https://lore.kernel.org/r/20210930131120.6ddfc603aa1d.I2137344c4e2426525b1a8e4ce5fca82f8ecbfe7e@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/wireless/scan.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)

--- a/net/wireless/scan.c
+++ b/net/wireless/scan.c
@@ -418,14 +418,17 @@ cfg80211_add_nontrans_list(struct cfg802
}
ssid_len = ssid[1];
ssid = ssid + 2;
- rcu_read_unlock();

/* check if nontrans_bss is in the list */
list_for_each_entry(bss, &trans_bss->nontrans_list, nontrans_list) {
- if (is_bss(bss, nontrans_bss->bssid, ssid, ssid_len))
+ if (is_bss(bss, nontrans_bss->bssid, ssid, ssid_len)) {
+ rcu_read_unlock();
return 0;
+ }
}

+ rcu_read_unlock();
+
/* add to the list */
list_add_tail(&nontrans_bss->nontrans_list, &trans_bss->nontrans_list);
return 0;