wifi: cfg80211: fix double free for link_sinfo in nl80211_station_dump()

Currently, the link_sinfo structure is being freed twice in
nl80211_dump_station(), once after the send_station() call and again
in the error handling path. This results in a double free of both
link_sinfo and link_sinfo->pertid, which might lead to undefined
behavior or kernel crashes.

Hence, fix by ensuring cfg80211_sinfo_release_content() is only
invoked once during execution of nl80211_station_dump().

Fixes: 49e47223ecc4 ("wifi: cfg80211: allocate memory for link_station info structure")
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: https://lore.kernel.org/all/81f30515-a83d-4b05-a9d1-e349969df9e9@sabinyo.mountain/
Reported-by: syzbot+4ba6272678aa468132c8@syzkaller.appspotmail.com
Closes: https://lore.kernel.org/all/68655325.a70a0220.5d25f.0316.GAE@google.com
Signed-off-by: Sarika Sharma <quic_sarishar@quicinc.com>
Link: https://patch.msgid.link/20250714084405.178066-1-quic_sarishar@quicinc.com
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

diff --git a/net/wireless/nl80211.c b/net/wireless/nl80211.c
index e1df03e8ed5c1ef10e6428251155c16c374d4549..63f015ce9ad41883f418760786d2cd7955ed8de1 100644 (file)
--- a/net/wireless/nl80211.c
+++ b/net/wireless/nl80211.c
@@ -7451,6 +7451,7 @@ static int nl80211_dump_station(struct sk_buff *skb,
        struct wireless_dev *wdev;
        u8 mac_addr[ETH_ALEN];
        int sta_idx = cb->args[2];
+       bool sinfo_alloc = false;
        int err, i;
 
        err = nl80211_prepare_wdev_dump(cb, &rdev, &wdev, NULL);
@@ -7479,6 +7480,7 @@ static int nl80211_dump_station(struct sk_buff *skb,
                                err = -ENOMEM;
                                goto out_err;
                        }
+                       sinfo_alloc = true;
                }
 
                err = rdev_dump_station(rdev, wdev->netdev, sta_idx,
@@ -7491,6 +7493,11 @@ static int nl80211_dump_station(struct sk_buff *skb,
                if (sinfo.valid_links)
                        cfg80211_sta_set_mld_sinfo(&sinfo);
 
+               /* reset the sinfo_alloc flag as nl80211_send_station()
+                * always releases sinfo
+                */
+               sinfo_alloc = false;
+
                if (nl80211_send_station(skb, NL80211_CMD_NEW_STATION,
                                NETLINK_CB(cb->skb).portid,
                                cb->nlh->nlmsg_seq, NLM_F_MULTI,
@@ -7505,7 +7512,8 @@ static int nl80211_dump_station(struct sk_buff *skb,
        cb->args[2] = sta_idx;
        err = skb->len;
  out_err:
-       cfg80211_sinfo_release_content(&sinfo);
+       if (sinfo_alloc)
+               cfg80211_sinfo_release_content(&sinfo);
        wiphy_unlock(&rdev->wiphy);
 
        return err;