From patchwork Fri Jun 7 18:17:17 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Johannes Berg X-Patchwork-Id: 802580 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B31BE20328 for ; Fri, 7 Jun 2024 18:17:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717784255; cv=none; b=M2bcgVV0LUI1iUjsuYAbWMXwSMjA/KVKvgiR8BUyYaJU/WtiIL7zUnUXr0PDR04wbl/Wdk/8ttLygAz8RAGcQZ+LzFDO9seUOxS5KOplP+ROGua0PD6lYc4zWz4o+6uHqHhU5Cq63hlQYdt5sBr1C//H9k+isBcVTcP5SWZLKZU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717784255; c=relaxed/simple; bh=0jMXe772U0kEu4+svUG7QhkVWWcmfuU0CghXpR40F+s=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=qFdwbaYtikkYnnLy9YECX6DrxJGnO7P+L9OWrlsJ+ht9MARvZwIkDcgdFvpLXCdCBNJ70rz1IMTi5IV0S7fd2sOT6IOLLtOp67wCysdoos8VRnz0lgrHreFHangRLe+JsEsgYQcD6+t1Htnz1PvEED7YVOerq+jKLHyFJxhnwAA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=ShmjWLKK; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="ShmjWLKK" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=Content-Transfer-Encoding:MIME-Version: Message-ID:Date:Subject:Cc:To:From:Content-Type:Sender:Reply-To:Content-ID: Content-Description:Resent-Date:Resent-From:Resent-To:Resent-Cc: Resent-Message-ID:In-Reply-To:References; bh=DJaAfeQoMYs56G95x6nzqWoKtWm9btBU54CELr3rkCg=; t=1717784253; x=1718993853; b=ShmjWLKK1H+SlZtZQ544dciNACKp592I+pCPMVqxGzQwog1WLLtIm4MBWKJQilqpHOk0QmXOQHb Ds+PahM+VbmP9CSIqgyuQe3zxqP2dTtQdEu3SIrlrPj9WSaIdn7sNQfeqf3dzQXc4eupHQunNwl/3 vtavGcFmyYqgeMuzQHlzzJK+Z1zVgUQGaWxEhXwN0z54CXUcZnfudKU0OHsoI7OoGt5tVjNNsAfLN 4C8UWH1dmYhVbBFCA96dkUVqA+hXMLFgrlcOScjqxg06MUgBB6ffMAFwxGXl/5IdEDBXDRyQHZzQx Gg/14NtKTaD/t97XEOTYWvTBBq2OkIR8WEEw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.97) (envelope-from ) id 1sFe9a-00000001Rs2-0y0K; Fri, 07 Jun 2024 20:17:30 +0200 From: Johannes Berg To: linux-wireless@vger.kernel.org Cc: Jiazi Li , Jiazi Li , Johannes Berg Subject: [PATCH] wifi: cfg80211: make hash table duplicates more survivable Date: Fri, 7 Jun 2024 20:17:17 +0200 Message-ID: <20240607181726.36835-2-johannes@sipsolutions.net> X-Mailer: git-send-email 2.45.2 Precedence: bulk X-Mailing-List: linux-wireless@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Johannes Berg Jiazi Li reported that they occasionally see hash table duplicates as evidenced by the WARN_ON() in rb_insert_bss() in this code. It isn't clear how that happens, nor have I been able to reproduce it, but if it does happen, the kernel crashes later, when it tries to unhash the entry that's now not hashed. Try to make this situation more survivable by removing the BSS from the list(s) as well, that way it's fully leaked here (as had been the intent in the hash insert error path), and no longer reachable through the list(s) so it shouldn't be unhashed again later. Link: https://lore.kernel.org/r/20231026013528.GA24122@Jiazi.Li Signed-off-by: Johannes Berg --- net/wireless/scan.c | 46 +++++++++++++++++++++++++++++++++------------ 1 file changed, 34 insertions(+), 12 deletions(-) diff --git a/net/wireless/scan.c b/net/wireless/scan.c index 127853877a0a..f02e8880da50 100644 --- a/net/wireless/scan.c +++ b/net/wireless/scan.c @@ -1589,7 +1589,7 @@ struct cfg80211_bss *__cfg80211_get_bss(struct wiphy *wiphy, } EXPORT_SYMBOL(__cfg80211_get_bss); -static void rb_insert_bss(struct cfg80211_registered_device *rdev, +static bool rb_insert_bss(struct cfg80211_registered_device *rdev, struct cfg80211_internal_bss *bss) { struct rb_node **p = &rdev->bss_tree.rb_node; @@ -1605,7 +1605,7 @@ static void rb_insert_bss(struct cfg80211_registered_device *rdev, if (WARN_ON(!cmp)) { /* will sort of leak this BSS */ - return; + return false; } if (cmp < 0) @@ -1616,6 +1616,7 @@ static void rb_insert_bss(struct cfg80211_registered_device *rdev, rb_link_node(&bss->rbn, parent, p); rb_insert_color(&bss->rbn, &rdev->bss_tree); + return true; } static struct cfg80211_internal_bss * @@ -1642,6 +1643,34 @@ rb_find_bss(struct cfg80211_registered_device *rdev, return NULL; } +static void cfg80211_insert_bss(struct cfg80211_registered_device *rdev, + struct cfg80211_internal_bss *bss) +{ + lockdep_assert_held(&rdev->bss_lock); + + if (!rb_insert_bss(rdev, bss)) + return; + list_add_tail(&bss->list, &rdev->bss_list); + rdev->bss_entries++; +} + +static void cfg80211_rehash_bss(struct cfg80211_registered_device *rdev, + struct cfg80211_internal_bss *bss) +{ + lockdep_assert_held(&rdev->bss_lock); + + rb_erase(&bss->rbn, &rdev->bss_tree); + if (!rb_insert_bss(rdev, bss)) { + list_del(&bss->list); + if (!list_empty(&bss->hidden_list)) + list_del_init(&bss->hidden_list); + if (!list_empty(&bss->pub.nontrans_list)) + list_del_init(&bss->pub.nontrans_list); + rdev->bss_entries--; + } + rdev->bss_generation++; +} + static bool cfg80211_combine_bsses(struct cfg80211_registered_device *rdev, struct cfg80211_internal_bss *new) { @@ -1954,9 +1983,7 @@ __cfg80211_bss_update(struct cfg80211_registered_device *rdev, bss_ref_get(rdev, bss_from_pub(tmp->pub.transmitted_bss)); } - list_add_tail(&new->list, &rdev->bss_list); - rdev->bss_entries++; - rb_insert_bss(rdev, new); + cfg80211_insert_bss(rdev, new); found = new; } @@ -3333,19 +3360,14 @@ void cfg80211_update_assoc_bss_entry(struct wireless_dev *wdev, if (!WARN_ON(!__cfg80211_unlink_bss(rdev, new))) rdev->bss_generation++; } - - rb_erase(&cbss->rbn, &rdev->bss_tree); - rb_insert_bss(rdev, cbss); - rdev->bss_generation++; + cfg80211_rehash_bss(rdev, cbss); list_for_each_entry_safe(nontrans_bss, tmp, &cbss->pub.nontrans_list, nontrans_list) { bss = bss_from_pub(nontrans_bss); bss->pub.channel = chan; - rb_erase(&bss->rbn, &rdev->bss_tree); - rb_insert_bss(rdev, bss); - rdev->bss_generation++; + cfg80211_rehash_bss(rdev, bss); } done: