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 042ED438FEE; Tue, 21 Jul 2026 21:44:35 +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=1784670276; cv=none; b=FRjXq6dS7hPBaVMbSAk8GtMukNq2ZJWN1yWIRuPZh05B0nV3uhIHdYcbsjT9YgOyjZ2jrNd6BJGFzKr0Oz1Lsx+gxt3BZYypeTvMcmD7qtmFj8pWevNjqKSHmdo4idxTYY7gE1sZ1tnSl2TXbLc/1AGzEGGr1gJkkhh+3AUFGcc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784670276; c=relaxed/simple; bh=69hWt2MV3TtlEkDoR56Xrsk23Gg2D/lgGyqTDUykkBg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uRH6YrILPE8zAaL5yb5N5GoMpanBa8WYNbuuG3SC9Wug8okKhZJOA1wZLzB8WjHDBZ4wm/bF3A3oFAfqqB+9u9WTK4KolUUillC4DfuWJLgPrsSiAZpOuyfutOzgMb8++7XtfOeUNfuuOoE3VENnxG9twIyKVIHEeWb9Vs6Dojk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=f545FVZo; 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="f545FVZo" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 695301F00A3A; Tue, 21 Jul 2026 21:44:34 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784670274; bh=XcZmPcvoNH2yp2A2hPHQJDdpMipQ7vT/k5PBc0bEcE4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=f545FVZoNQcy5/yoyOtca7R0IipoTDQ5Yx0EiNRXpWaI8mJjB58FZtSvKJwTJY34H fwe9WUGv6EFd5FMKL/jRjHGcNoeYpa21pITwsZoYOrUowqofr00C4BZEHsoxcLEmQJ KJiJriDLp1t6yLGV+N8HunexHC0rf/np43PSUGcI= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Doruk Tan Ozturk , Tariq Toukan , Jakub Kicinski Subject: [PATCH 6.1 0870/1067] net/mlx5e: macsec: fix use-after-free of metadata_dst on RX SC delete Date: Tue, 21 Jul 2026 17:24:31 +0200 Message-ID: <20260721152443.997956973@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152424.521567757@linuxfoundation.org> References: <20260721152424.521567757@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 6.1-stable review patch. If anyone has any objections, please let me know. ------------------ From: Doruk Tan Ozturk commit de74d8fd10291763d97b218f09adcc7513c975e4 upstream. When an offloaded MACsec RX SC is deleted, macsec_del_rxsc_ctx() freed the per-SC metadata_dst with metadata_dst_free(), which kfree()s the object unconditionally and ignores the dst reference count. The RX datapath in mlx5e_macsec_offload_handle_rx_skb() looks up the SC under rcu_read_lock() via xa_load(), takes a reference with dst_hold() and attaches the dst to the skb with skb_dst_set(). A reader that already obtained the rx_sc pointer can race with the delete path and operate on freed memory. Fix the owner side by dropping the reference with dst_release() instead of freeing unconditionally, and convert the RX datapath to dst_hold_safe() so a reader racing the SC delete cannot attach a dst whose last reference was just dropped; only attach it when a reference was actually taken. mlx5e_macsec_add_rxsc() also published sc_xarray_element via xa_alloc() before rx_sc->md_dst was allocated and initialised, so a datapath reader that looked the SC up by fs_id could observe rx_sc with md_dst still NULL or, on weakly-ordered architectures, a non-NULL md_dst pointer whose contents were not yet visible. NULL-check the xa_load() result and md_dst on the datapath, and reorder add_rxsc() so the xa_alloc() publish happens only after md_dst is fully initialised; the xarray RCU publish then pairs with the rcu_read_lock()/xa_load() in the datapath. Note: macsec_del_rxsc_ctx() also kfree()s rx_sc->sc_xarray_element without an RCU grace period while the same datapath reads it under rcu_read_lock(); that is a separate pre-existing issue left to a follow-up patch. Found by 0sec automated security-research tooling (https://0sec.ai). Fixes: b7c9400cbc48 ("net/mlx5e: Implement MACsec Rx data path using MACsec skb_metadata_dst") Cc: stable@vger.kernel.org Signed-off-by: Doruk Tan Ozturk Reviewed-by: Tariq Toukan Link: https://patch.msgid.link/20260627223059.29917-1-doruk@0sec.ai Signed-off-by: Jakub Kicinski Signed-off-by: Greg Kroah-Hartman --- drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c | 47 ++++++++------ 1 file changed, 28 insertions(+), 19 deletions(-) --- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c @@ -735,34 +735,43 @@ static int mlx5e_macsec_add_rxsc(struct } sc_xarray_element->rx_sc = rx_sc; - err = xa_alloc(&macsec->sc_xarray, &sc_xarray_element->fs_id, sc_xarray_element, - XA_LIMIT(1, MLX5_MACEC_RX_FS_ID_MAX), GFP_KERNEL); - if (err) { - if (err == -EBUSY) - netdev_err(ctx->netdev, - "MACsec offload: unable to create entry for RX SC (%d Rx SCs already allocated)\n", - MLX5_MACEC_RX_FS_ID_MAX); - goto destroy_sc_xarray_elemenet; - } rx_sc->md_dst = metadata_dst_alloc(0, METADATA_MACSEC, GFP_KERNEL); if (!rx_sc->md_dst) { err = -ENOMEM; - goto erase_xa_alloc; + goto destroy_sc_xarray_elemenet; } rx_sc->sci = ctx_rx_sc->sci; rx_sc->active = ctx_rx_sc->active; - list_add_rcu(&rx_sc->rx_sc_list_element, rx_sc_list); - rx_sc->sc_xarray_element = sc_xarray_element; rx_sc->md_dst->u.macsec_info.sci = rx_sc->sci; + + /* + * Publish the fully-initialised SC last: xa_alloc() makes + * sc_xarray_element->rx_sc (and rx_sc->md_dst) reachable from the RX + * datapath via xa_load(). Doing it only after md_dst is allocated and + * initialised pairs with the rcu_read_lock()/xa_load() in + * mlx5e_macsec_offload_handle_rx_skb(), so a reader can never observe + * a non-NULL md_dst with uninitialised contents. + */ + err = xa_alloc(&macsec->sc_xarray, &sc_xarray_element->fs_id, sc_xarray_element, + XA_LIMIT(1, MLX5_MACEC_RX_FS_ID_MAX), GFP_KERNEL); + if (err) { + if (err == -EBUSY) + netdev_err(ctx->netdev, + "MACsec offload: unable to create entry for RX SC (%d Rx SCs already allocated)\n", + MLX5_MACEC_RX_FS_ID_MAX); + goto destroy_md_dst; + } + + list_add_rcu(&rx_sc->rx_sc_list_element, rx_sc_list); mutex_unlock(&macsec->lock); return 0; -erase_xa_alloc: - xa_erase(&macsec->sc_xarray, sc_xarray_element->fs_id); +destroy_md_dst: + dst_release(&rx_sc->md_dst->dst); destroy_sc_xarray_elemenet: kfree(sc_xarray_element); destroy_rx_sc: @@ -847,7 +856,7 @@ static void macsec_del_rxsc_ctx(struct m */ list_del_rcu(&rx_sc->rx_sc_list_element); xa_erase(&macsec->sc_xarray, rx_sc->sc_xarray_element->fs_id); - metadata_dst_free(rx_sc->md_dst); + dst_release(&rx_sc->md_dst->dst); kfree(rx_sc->sc_xarray_element); kfree_rcu(rx_sc); } @@ -1755,10 +1764,10 @@ void mlx5e_macsec_offload_handle_rx_skb( rcu_read_lock(); sc_xarray_element = xa_load(&macsec->sc_xarray, fs_id); - rx_sc = sc_xarray_element->rx_sc; - if (rx_sc) { - dst_hold(&rx_sc->md_dst->dst); - skb_dst_set(skb, &rx_sc->md_dst->dst); + rx_sc = sc_xarray_element ? sc_xarray_element->rx_sc : NULL; + if (rx_sc && rx_sc->md_dst) { + if (dst_hold_safe(&rx_sc->md_dst->dst)) + skb_dst_set(skb, &rx_sc->md_dst->dst); } rcu_read_unlock();