From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E3F043D9DAA; Wed, 8 Apr 2026 18:23:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775672590; cv=none; b=pH/Yn1d8YdUPKpafA1os9T7niMO1jd4T9bz1iYEKWH7ymyom7Aq2f8eGmNQM7ZlYmuNGZ5ZEsT695lTE2jB9YPrURh2ShWNdnh4Ez0Z/fkXiF0myrgWFwvn/aEfrcka3KadQGcBJdD0AumNAQCCkT4CXvDudcuNoFU4aXPy6s2A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775672590; c=relaxed/simple; bh=UMH555z18tYQ6Dmho8yWUIdoOI4drJMsmo6pI67nJPs=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=D5xPs1+1MGbIZ12pwhuZCRFO/KM6RMXOIpySYbivUIKA7BA8PyTlTeXOD2A7l4hh/eUVdTxHFu6OqFTT1+PSxYk1Arz1X1Rtauxryh5vzdqf214F5HbILnhaWVRZ/SoL3ROV71rw0XTRJZOObEeB6dxx/NdDJV0ow9mp6jjEdYc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=I1rYN41J; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="I1rYN41J" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 37BA8C19421; Wed, 8 Apr 2026 18:23:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775672589; bh=UMH555z18tYQ6Dmho8yWUIdoOI4drJMsmo6pI67nJPs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=I1rYN41JPWFkEOLRnqWpqE67DheUbVeEYuDuvfUSyDvO79lzwaPXDCmSxK+u0wBsE I3LuWPDV5IL+iXJI+IWWbHNB2UW4BdMqw5mFeYlYT1Wk2lXoIefQFGyAFJOuE+8xQ0 UNlWWaa/hMjXDoSewl0lE6tCLxb5ehbMCyF8yghw= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Yifan Wu , Juefei Pu , Yuan Tan , Xin Liu , Ren Wei , Zhengchuan Liang , Ren Wei , Eric Dumazet , Jakub Kicinski , Sasha Levin Subject: [PATCH 6.6 033/160] net: ipv6: flowlabel: defer exclusive option free until RCU teardown Date: Wed, 8 Apr 2026 20:02:00 +0200 Message-ID: <20260408175914.447442348@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175913.177092714@linuxfoundation.org> References: <20260408175913.177092714@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zhengchuan Liang [ Upstream commit 9ca562bb8e66978b53028fa32b1a190708e6a091 ] `ip6fl_seq_show()` walks the global flowlabel hash under the seq-file RCU read-side lock and prints `fl->opt->opt_nflen` when an option block is present. Exclusive flowlabels currently free `fl->opt` as soon as `fl->users` drops to zero in `fl_release()`. However, the surrounding `struct ip6_flowlabel` remains visible in the global hash table until later garbage collection removes it and `fl_free_rcu()` finally tears it down. A concurrent `/proc/net/ip6_flowlabel` reader can therefore race that early `kfree()` and dereference freed option state, triggering a crash in `ip6fl_seq_show()`. Fix this by keeping `fl->opt` alive until `fl_free_rcu()`. That matches the lifetime already required for the enclosing flowlabel while readers can still reach it under RCU. Fixes: d3aedd5ebd4b ("ipv6 flowlabel: Convert hash list to RCU.") Reported-by: Yifan Wu Reported-by: Juefei Pu Co-developed-by: Yuan Tan Signed-off-by: Yuan Tan Suggested-by: Xin Liu Tested-by: Ren Wei Signed-off-by: Zhengchuan Liang Signed-off-by: Ren Wei Reviewed-by: Eric Dumazet Link: https://patch.msgid.link/07351f0ec47bcee289576f39f9354f4a64add6e4.1774855883.git.zcliangcn@gmail.com Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- net/ipv6/ip6_flowlabel.c | 5 ----- 1 file changed, 5 deletions(-) diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c index b3ca4beb4405a..bf909fa69a977 100644 --- a/net/ipv6/ip6_flowlabel.c +++ b/net/ipv6/ip6_flowlabel.c @@ -133,11 +133,6 @@ static void fl_release(struct ip6_flowlabel *fl) if (time_after(ttd, fl->expires)) fl->expires = ttd; ttd = fl->expires; - if (fl->opt && fl->share == IPV6_FL_S_EXCL) { - struct ipv6_txoptions *opt = fl->opt; - fl->opt = NULL; - kfree(opt); - } if (!timer_pending(&ip6_fl_gc_timer) || time_after(ip6_fl_gc_timer.expires, ttd)) mod_timer(&ip6_fl_gc_timer, ttd); -- 2.53.0