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UPSTREAM: wifi: cfg80211: fix BSS refcounting bugs

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commit 0b7808818cb9df6680f98996b8e9a439fa7bcc2f upstream.

There are multiple refcounting bugs related to multi-BSSID:
 - In bss_ref_get(), if the BSS has a hidden_beacon_bss, then
   the bss pointer is overwritten before checking for the
   transmitted BSS, which is clearly wrong. Fix this by using
   the bss_from_pub() macro.

 - In cfg80211_bss_update() we copy the transmitted_bss pointer
   from tmp into new, but then if we release new, we'll unref
   it erroneously. We already set the pointer and ref it, but
   need to NULL it since it was copied from the tmp data.

 - In cfg80211_inform_single_bss_data(), if adding to the non-
   transmitted list fails, we unlink the BSS and yet still we
   return it, but this results in returning an entry without
   a reference. We shouldn't return it anyway if it was broken
   enough to not get added there.

This fixes CVE-2022-42720.

Bug: 253642015
Reported-by: Sönke Huster <shuster@seemoo.tu-darmstadt.de>
Tested-by: Sönke Huster <shuster@seemoo.tu-darmstadt.de>
Fixes: a3584f56de ("cfg80211: Properly track transmitting and non-transmitting BSS")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Lee Jones <joneslee@google.com>
Change-Id: I0389708d1ada86ab2fa0a7ada203b71f789c506b
This commit is contained in:
Johannes Berg 2022-09-30 23:44:23 +02:00 committed by Treehugger Robot
parent a30ebebb22
commit 916a29b486
1 changed files with 14 additions and 13 deletions
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27
net/wireless/scan.c
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@ -104,18 +104,12 @@ static inline void bss_ref_get(struct cfg80211_registered_device *rdev,
lockdep_assert_held(&rdev->bss_lock);
bss->refcount++;
if (bss->pub.hidden_beacon_bss) {
bss = container_of(bss->pub.hidden_beacon_bss,
struct cfg80211_internal_bss,
pub);
bss->refcount++;
}
if (bss->pub.transmitted_bss) {
bss = container_of(bss->pub.transmitted_bss,
struct cfg80211_internal_bss,
pub);
bss->refcount++;
}
if (bss->pub.hidden_beacon_bss)
bss_from_pub(bss->pub.hidden_beacon_bss)->refcount++;
if (bss->pub.transmitted_bss)
bss_from_pub(bss->pub.transmitted_bss)->refcount++;
}
static inline void bss_ref_put(struct cfg80211_registered_device *rdev,
@ -1247,6 +1241,8 @@ cfg80211_bss_update(struct cfg80211_registered_device *rdev,
new->refcount = 1;
INIT_LIST_HEAD(&new->hidden_list);
INIT_LIST_HEAD(&new->pub.nontrans_list);
/* we'll set this later if it was non-NULL */
new->pub.transmitted_bss = NULL;
if (rcu_access_pointer(tmp->pub.proberesp_ies)) {
hidden = rb_find_bss(rdev, tmp, BSS_CMP_HIDE_ZLEN);
@ -1476,10 +1472,15 @@ cfg80211_inform_single_bss_data(struct wiphy *wiphy,
spin_lock_bh(&rdev->bss_lock);
if (cfg80211_add_nontrans_list(non_tx_data->tx_bss,
&res->pub)) {
if (__cfg80211_unlink_bss(rdev, res))
if (__cfg80211_unlink_bss(rdev, res)) {
rdev->bss_generation++;
res = NULL;
}
}
spin_unlock_bh(&rdev->bss_lock);
if (!res)
return NULL;
}
trace_cfg80211_return_bss(&res->pub);