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 7D1522DCF41; Wed, 8 Apr 2026 18:15:13 +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=1775672113; cv=none; b=WGrbXBOXjpmn5QUW4Co+daQRtJMpr4Usmj/Y8IvW4I6L17YG9/6InrbyHbo5UaS2dMNd09xwXKm5JrMoFZpqDOb48LAMC0CGsQkf8RWfI4VkmCBTLvmMez2GSA0K3K+tI4SBkvB3e+cd4i1KrxMGLOGssfLY7MspEstK2wSRsh8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775672113; c=relaxed/simple; bh=+lDqDuVSq8dawNOe2+NKF62fqt1vcSnDFbJiiPNVhGA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Kixijxb/qUMyCCw1O/HxRdzNxZFDRUy1EdeExGALeAtM8K4NnjaQkn619ztn+YlfTNHkYOy/TYx1pKnBUYJYtzjVsWDFva82yLBVfIjdNpwBSBwXjQQvavCx3RsZrO7MVdqdxTz9Muu3IqirxUis9dnMBItiq3g7fM1efxiCn3o= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=WkzWwbeU; 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="WkzWwbeU" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 135B0C19421; Wed, 8 Apr 2026 18:15:12 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1775672113; bh=+lDqDuVSq8dawNOe2+NKF62fqt1vcSnDFbJiiPNVhGA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WkzWwbeUIMNMjM9ERatgoj5KfNcZ/ca1dsEB3yMHRYCDaKe+yXwwWlFGFbSeLaSzn lrsny+WbVH+ya6MngxBBp3WU+WHrq8raSEHWU4Evo+1gBf0KxtOnck8Ec3yBJ/uwdL wibE5dw7cdQI/Ywkjbh2y/Ak9pVd0MmVm6bzmt9c= 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 6.1 162/312] net: ipv6: flowlabel: defer exclusive option free until RCU teardown Date: Wed, 8 Apr 2026 20:01:19 +0200 Message-ID: <20260408175939.815584525@linuxfoundation.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260408175933.715315542@linuxfoundation.org> References: <20260408175933.715315542@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 6.1-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 18481eb76a0a4..eb0d517aa6cb3 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