From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C81E8C4321E for ; Fri, 25 Mar 2022 15:25:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1354999AbiCYP10 (ORCPT ); Fri, 25 Mar 2022 11:27:26 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34166 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1377331AbiCYPYE (ORCPT ); Fri, 25 Mar 2022 11:24:04 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E9086E6C52; Fri, 25 Mar 2022 08:17:47 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 92866B8288D; Fri, 25 Mar 2022 15:17:45 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E0FD5C340E9; Fri, 25 Mar 2022 15:17:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1648221464; bh=tdXfN3dVELg7WjnAzE0xfkgquffdF7QCQ8MnLKjaJPU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=hDFZtOPC2KuNDClJKpv8Bu4JCJzcBYMvsw2OnpiR6fxR5F3LNhD7qVTLPr5bO71hF baOAXNfBryr5wf/Bg0ZJQiDPCXo9gWaObvqeHpUNG8jQPbKqzmru/ON20jKISGu9OU EetOxm3s5bwh1hEtXeQYXzDezbb2gMQvTDH4Kimc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Matthias Kretschmer , =?UTF-8?q?Linus=20L=C3=BCssing?= , Johannes Berg Subject: [PATCH 5.16 33/37] mac80211: fix potential double free on mesh join Date: Fri, 25 Mar 2022 16:14:43 +0100 Message-Id: <20220325150420.993855180@linuxfoundation.org> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220325150420.046488912@linuxfoundation.org> References: <20220325150420.046488912@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Linus Lüssing commit 4a2d4496e15ea5bb5c8e83b94ca8ca7fb045e7d3 upstream. While commit 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") fixed a memory leak on mesh leave / teardown it introduced a potential memory corruption caused by a double free when rejoining the mesh: ieee80211_leave_mesh() -> kfree(sdata->u.mesh.ie); ... ieee80211_join_mesh() -> copy_mesh_setup() -> old_ie = ifmsh->ie; -> kfree(old_ie); This double free / kernel panics can be reproduced by using wpa_supplicant with an encrypted mesh (if set up without encryption via "iw" then ifmsh->ie is always NULL, which avoids this issue). And then calling: $ iw dev mesh0 mesh leave $ iw dev mesh0 mesh join my-mesh Note that typically these commands are not used / working when using wpa_supplicant. And it seems that wpa_supplicant or wpa_cli are going through a NETDEV_DOWN/NETDEV_UP cycle between a mesh leave and mesh join where the NETDEV_UP resets the mesh.ie to NULL via a memcpy of default_mesh_setup in cfg80211_netdev_notifier_call, which then avoids the memory corruption, too. The issue was first observed in an application which was not using wpa_supplicant but "Senf" instead, which implements its own calls to nl80211. Fixing the issue by removing the kfree()'ing of the mesh IE in the mesh join function and leaving it solely up to the mesh leave to free the mesh IE. Cc: stable@vger.kernel.org Fixes: 6a01afcf8468 ("mac80211: mesh: Free ie data when leaving mesh") Reported-by: Matthias Kretschmer Signed-off-by: Linus Lüssing Tested-by: Mathias Kretschmer Link: https://lore.kernel.org/r/20220310183513.28589-1-linus.luessing@c0d3.blue Signed-off-by: Johannes Berg Signed-off-by: Greg Kroah-Hartman --- net/mac80211/cfg.c | 3 --- 1 file changed, 3 deletions(-) --- a/net/mac80211/cfg.c +++ b/net/mac80211/cfg.c @@ -2148,14 +2148,12 @@ static int copy_mesh_setup(struct ieee80 const struct mesh_setup *setup) { u8 *new_ie; - const u8 *old_ie; struct ieee80211_sub_if_data *sdata = container_of(ifmsh, struct ieee80211_sub_if_data, u.mesh); int i; /* allocate information elements */ new_ie = NULL; - old_ie = ifmsh->ie; if (setup->ie_len) { new_ie = kmemdup(setup->ie, setup->ie_len, @@ -2165,7 +2163,6 @@ static int copy_mesh_setup(struct ieee80 } ifmsh->ie_len = setup->ie_len; ifmsh->ie = new_ie; - kfree(old_ie); /* now copy the rest of the setup parameters */ ifmsh->mesh_id_len = setup->mesh_id_len;