[PATCH 5.12 159/178] cfg80211: avoid double free of PMSR request

Greg Kroah-Hartman
2021-06-21T16:51:23Z

From: Avraham Stern <avraham.stern@intel.com>

commit 0288e5e16a2e18f0b7e61a2b70d9037fc6e4abeb upstream.

If cfg80211_pmsr_process_abort() moves all the PMSR requests that
need to be freed into a local list before aborting and freeing them.
As a result, it is possible that cfg80211_pmsr_complete() will run in
parallel and free the same PMSR request.

Fix it by freeing the request in cfg80211_pmsr_complete() only if it
is still in the original pmsr list.

Cc: stable@vger.kernel.org
Fixes: 9bb7e0f24e7e ("cfg80211: add peer measurement with FTM initiator API")
Signed-off-by: Avraham Stern <avraham.stern@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210618133832.1fbef57e269a.I00294bebdb0680b892f8d1d5c871fd9dbe785a5e@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
net/wireless/pmsr.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)

--- a/net/wireless/pmsr.c
+++ b/net/wireless/pmsr.c
@@ -324,6 +324,7 @@ void cfg80211_pmsr_complete(struct wirel
gfp_t gfp)
{
struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
+ struct cfg80211_pmsr_request *tmp, *prev, *to_free = NULL;
struct sk_buff *msg;
void *hdr;

@@ -354,9 +355,20 @@ free_msg:
nlmsg_free(msg);
free_request:
spin_lock_bh(&wdev->pmsr_lock);
- list_del(&req->list);
+ /*
+ * cfg80211_pmsr_process_abort() may have already moved this request
+ * to the free list, and will free it later. In this case, don't free
+ * it here.
+ */
+ list_for_each_entry_safe(tmp, prev, &wdev->pmsr_list, list) {
+ if (tmp == req) {
+ list_del(&req->list);
+ to_free = req;
+ break;
+ }
+ }
spin_unlock_bh(&wdev->pmsr_lock);
- kfree(req);
+ kfree(to_free);
}
EXPORT_SYMBOL_GPL(cfg80211_pmsr_complete);