[PATCH 06/31] cfg80211: avoid double free of PMSR request
From: Luca Coelho <hidden>
Date: 2021-06-18 10:42:11
Subsystem:
802.11 (including cfg80211/nl80211), the rest · Maintainers:
Johannes Berg, Linus Torvalds
From: Avraham Stern <redacted> 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. Signed-off-by: Avraham Stern <redacted> Signed-off-by: Luca Coelho <redacted> --- net/wireless/pmsr.c | 16 ++++++++++++++-- 1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/net/wireless/pmsr.c b/net/wireless/pmsr.c
index 6bdd96408022..d245968b74cb 100644
--- a/net/wireless/pmsr.c
+++ b/net/wireless/pmsr.c@@ -334,6 +334,7 @@ void cfg80211_pmsr_complete(struct wireless_dev *wdev, 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;
@@ -364,9 +365,20 @@ void cfg80211_pmsr_complete(struct wireless_dev *wdev, 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);
--
2.32.0