From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793111167; b=5tx28PMCcNlFtNzUoMuRMxhh0HEX/4tR6DzMvdtqhUz/2ohxZqw72EzS597hDmlQGvY1 LczUIkt1aLV/Q9SY3Jbz9Fuaz7+h8hBXRg6xsHbLoTb+o1xp9U8PiFwypL3WSha87MgsB sQ2AvR+vIRq/pHQdOT8FwlfP0G9HLvdHouH8hpgzf+FGJ8q79OpS5Zg55TWH3AwQCAWWi FPozWxgGkPvVjSUYzOZbGx6Y+1OWM3wcOLrm3o0p+1dk/R3b/B6hoxnmGw9NRBPqcm0M8 dHkMtALumX5alSmE2IqeOlPdGNxP6yDPKMXirmRti33vkngjf2sY61la0dt44dsxTLg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793111167; h=Received:DKIM-Signature:Date:From:To:Cc:Subject:Message-ID: References:MIME-Version:Content-Type:Content-Disposition:In-Reply-To; bh=z27crQTjHzX0wxvWS41zGiz/0QWCCGhHzWTW1/KXN7I=; b=cR3uCIzqy2uC5DbgbDnMT4x/SwQnPH6ngM3BVoDofTTcY5mNgNoriCfCxQtj9BAOxHSf 7D+HRft9aSZgHQ5ViUlOmtrte/WVuwjElNkPt5N9D6E3V6lfIYs6u5CJcZ6fYVI8kbLBs NkL6Q4+SBe2uR12R7HNMlJuscG+XB20NKPhjH2Mh8F+jqtUQjWhKSVUSJLXggLsPzO4sD XRQTtRsKbKsr39nSjRJI2GTy7+ooBXECid1qkzI/gjSKOtmsT7UOkRzgCu89AoRtWAA7M xWZda/o/0UroVvMKl9bqWw2WBc0l7adH222gZWiFLkiZoC1Sv8WKYADC1xzTkaVfDJA== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=JMtpTDrF; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 51BD3606A31A; Tue, 27 Oct 2026 14:26:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=JMtpTDrF Received: by smtp.kernel.org (Postfix) with ESMTPSA id 5896A1F01825; Tue, 27 Oct 2026 14:26:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793111166; bh=z27crQTjHzX0wxvWS41zGiz/0QWCCGhHzWTW1/KXN7I=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=JMtpTDrF7fiu7lDnMsUp94Cm+JN1Fy3FyhF04TMzNSoaY3KCMum3ks0k+Z8LNcD1+ LytnrXmA0L6MKn1657mK5HoWy+CeAHoIuVcict2nwF+WSUNB/1hEwuz1BwtTU6EOo9 U4b5LoIsFZBBtrGpFMo/8dYLjeMEbcY2DGWANS34JtaU9hhXNbXHXhliMU6ghaGFtx fRwNuUm1l508qzA3qxRkfekH6d5IHKKdfrVapJg8ZQ/Jt4HQcsX8Z0n/qXJENzBPnR Qbky46Y0NvH+kZTCVozpfldbogvBRwhkDkCA9Zw8NJeHhOqh95K1BxP1teF8yHore6 Aq5IpExvqeVFQ== Date: Tue, 27 Oct 2026 14:26:01 +0000 From: Simon Horman To: Joas Antonio dos Santos Cc: Saeed Mahameed , Tariq Toukan , Leon Romanovsky , Mark Bloch , Boris Pismenny , Sabrina Dubroca , Andrew Lunn , "David S. Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , netdev@vger.kernel.org, linux-rdma@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH net] net/mlx5e: macsec: free SC lookup entries after an RCU grace period Message-ID: <20261027142601.GM257209@horms.kernel.org> References: <179285888829.90275.17386097105525068016@gmail.com> X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <179285888829.90275.17386097105525068016@gmail.com> On Sat, Oct 24, 2026 at 01:21:28PM -0300, Joas Antonio dos Santos wrote: > macsec_del_rxsc_ctx() removes rx_sc->sc_xarray_element from > macsec->sc_xarray with xa_erase() and frees it with kfree() right away. > mlx5e_macsec_offload_handle_rx_skb() looks the element up with > xa_load() under rcu_read_lock() and then dereferences ->rx_sc, so an RX > completion that loaded the element just before xa_erase() reads freed > memory. rx_sc itself is already freed with kfree_rcu_mightsleep(); only > the element pointing to it was missed. > > macsec_fs_id_del() has the same problem on the TX side: it removes > fs_id_found from the SCI rhashtable and frees it with kfree(), while > mlx5e_macsec_handle_tx_skb() and mlx5e_macsec_tx_build_eseg() read it > through mlx5_macsec_fs_get_fs_id_from_hashtable(), which uses > rhashtable_lookup() under rcu_read_lock(). > > Free both with kvfree_rcu_mightsleep(). Both run in process context > from the macsec offload ops, outside any spinlock, so sleeping is fine. > > The sc_xarray_element issue was pointed out during review of > "net/mlx5e: macsec: fix use-after-free of metadata_dst on RX SC delete" > and left for a follow-up; this is that follow-up. > > Fixes: b7c9400cbc48 ("net/mlx5e: Implement MACsec Rx data path using MACsec skb_metadata_dst") > Signed-off-by: Joas Antonio dos Santos > Assisted-by: Yaga Agent HackerSec Claude:claude-opus-5-5 > --- > Testing: compile-tested only (arm64, W=1, CONFIG_MLX5_MACSEC=y, no new > warnings). I do not have MACsec-capable ConnectX hardware, so this was > not run on a real device and I have no reproducer against the driver > itself. The free-while-reader-holds-RCU pattern was reproduced with a > standalone test module under KASAN (slab-use-after-free on kmalloc-16), > and the same module showed no reports after switching to > kvfree_rcu_mightsleep(). > > drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c | 2 +- > drivers/net/ethernet/mellanox/mlx5/core/lib/macsec_fs.c | 2 +- > 2 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c > index 38a3415ac..fb9126f6b 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/en_accel/macsec.c > @@ -839,7 +839,7 @@ static void macsec_del_rxsc_ctx(struct mlx5e_macsec *macsec, struct mlx5e_macsec > list_del_rcu(&rx_sc->rx_sc_list_element); > xa_erase(&macsec->sc_xarray, rx_sc->sc_xarray_element->fs_id); > dst_release(&rx_sc->md_dst->dst); > - kfree(rx_sc->sc_xarray_element); > + kvfree_rcu_mightsleep(rx_sc->sc_xarray_element); > kfree_rcu_mightsleep(rx_sc); > } > Hi Joas, This patch does not apply because the problem in macsec_del_rxsc_ctx() has already been addressed by ad17ad50b8dc ("net: mlx5e: Fix use-after-free of the MACsec xarray entry on RX SC deletion") using kfree_rcu. I would suggest taking that approach in macsec_fs_id_del() too unless there is a reason to use mightsleep. Quoting the documentation of kfree_rcu_mightsleep(): /** * kfree_rcu_mightsleep() - kfree an object after a grace period. * @ptr: pointer to kfree for single-argument invocations. * * When it comes to head-less variant, only one argument * is passed and that is just a pointer which has to be * freed after a grace period. Therefore the semantic is * * kfree_rcu_mightsleep(ptr); * * where @ptr is the pointer to be freed by kvfree(). * * Please note, head-less way of freeing is permitted to * use from a context that has to follow might_sleep() * annotation. Otherwise, please switch and embed the * rcu_head structure within the type of @ptr. */ > diff --git a/drivers/net/ethernet/mellanox/mlx5/core/lib/macsec_fs.c b/drivers/net/ethernet/mellanox/mlx5/core/lib/macsec_fs.c > index efc516749..910fafe40 100644 > --- a/drivers/net/ethernet/mellanox/mlx5/core/lib/macsec_fs.c > +++ b/drivers/net/ethernet/mellanox/mlx5/core/lib/macsec_fs.c > @@ -684,7 +684,7 @@ static void macsec_fs_id_del(struct list_head *macsec_devices_list, u32 fs_id, > > xa_erase(fs_id_xa, fs_id); > > - kfree(fs_id_found); > + kvfree_rcu_mightsleep(fs_id_found); > > if (macsec_fs_is_macsec_device_empty(macsec_device)) { > list_del(&macsec_device->macsec_devices_list_entry); -- pw-bot: changes-requested