From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 52756359A6C; Wed, 30 Sep 2026 19:13:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795630; cv=none; b=jBCs7NhZamTzwY+ynTDMSQu9h7QnSStZF/HfARMu3F+g6TkRSYdeZDh+npufpfzOH6J+V5x/HW4ZjuLIAgrBYhOpYceF0AoGu+folxUzT5tJocTY/tbsspZeBdVFCv1crtqI5MQAlDqfIN2E8U9IE42N50WxbOwxdfohJVDE+Xo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790795630; c=relaxed/simple; bh=+hvK2qeNMy9Qo5OO7THgxCzN9DHmST5KqIgZ4mkqJac=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=eUW3tu39z8NuVWu1DTS8MNi31Qe7BEO/Vab31zEaNQbxGb+jErgP3ACrmwlTZrJ4RhLLkPCCi4hMFuZPGj4ZdJHFuoS8jO4FcITkghmSlcNckH/pNE/LaGupa40m4eKOpAiTYMYYkw2TYu9OqQik/SPkWbavZeEhqnk8kMIeCuU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=tyBDPEfF; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="tyBDPEfF" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 982E61F000FF; Wed, 30 Sep 2026 19:13:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790795629; bh=Eo/hZ40HmLRBisMIyiIfD8pNpla1xmU7G1SRI72NeCk=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=tyBDPEfFb4WlqT9Y0VhwdbSvnvwDW9+/2lAhCF2qPJhl9IDauKWGh7gTDsh0Yy841 aekl+LMUDKGQhrN6ZjGTnrGW0z3nwuzylwKwJ5GWuywREm0E+gexAt+e7yhew+0n/a xJoX4/0iDk+ygBSmuxuaxawJEzSKpXauTRQkT70E= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Norbert Szetei , Ilya Maximets , Jakub Kicinski Subject: [PATCH 6.6 0629/1193] net: openvswitch: fix use-after-free of the flow table mask array Date: Wed, 30 Sep 2026 17:21:53 +0200 Message-ID: <20260930152448.218179697@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev 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: Norbert Szetei commit ba4ba11ed6eb8972c69070417fc27b48deb002e8 upstream. tbl_mask_array_realloc() retires the old mask_array before it stops being reachable: old = ovsl_dereference(tbl->mask_array); if (old) { ... call_rcu(&old->rcu, mask_array_rcu_cb); } rcu_assign_pointer(tbl->mask_array, new); call_rcu() only waits for read-side critical sections already in flight. tbl->mask_array still points at old between the call_rcu() and the rcu_assign_pointer(), so a reader entering ovs_flow_tbl_lookup_stats() in that window picks up old in a fresh critical section that the pending grace period does not cover. tbl_mask_array_realloc() runs in process context under ovs_mutex, so the window is preemptible and can outlast the grace period. Then mask_array_rcu_cb() frees old before the swap runs: BUG: KASAN: slab-use-after-free in flow_lookup.constprop.0+0x2bf/0x2f0 Read of size 8 at addr ffff888020b3e018 by task poc/741 flow_lookup.constprop.0+0x2bf/0x2f0 ovs_flow_tbl_lookup_stats+0x4a3/0x5c0 ovs_dp_process_packet+0x19c/0x710 ovs_vport_receive+0x243/0x390 internal_dev_xmit+0x81/0x170 Freed by task 728: kfree+0x16a/0x4e0 rcu_core+0x853/0x1030 Publish the new array before retiring the old one. The kfree_rcu() that call_rcu() replaced ran after the swap. Fixes: eac87c413bf9 ("net: openvswitch: reorder masks array based on usage") Cc: stable@vger.kernel.org Signed-off-by: Norbert Szetei Reviewed-by: Ilya Maximets Acked-by: Eelco Chaudron echaudro@redhat.com Link: https://patch.msgid.link/DE115F9C-2545-423E-A702-986FC952FD62@doyensec.com Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- net/openvswitch/flow_table.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) --- a/net/openvswitch/flow_table.c +++ b/net/openvswitch/flow_table.c @@ -262,11 +262,13 @@ static int tbl_mask_array_realloc(struct if (ovsl_dereference(old->masks[i])) new->masks[new->count++] = old->masks[i]; } - call_rcu(&old->rcu, mask_array_rcu_cb); } rcu_assign_pointer(tbl->mask_array, new); + if (old) + call_rcu(&old->rcu, mask_array_rcu_cb); + return 0; }