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 1892722969F; Wed, 11 Dec 2024 18:52:56 +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=1733943177; cv=none; b=ilMae1H4ow2YGcl00MFftYUVIAl56twviD8/Jg5IynijEby6EdsCrPYF9uFNiBiefFfxOptD4vm61brXWl8RJ4P59adcNjTnX3WLZAp9wj+0roHT//9uegXaY1RjGBD+FosbO2ZG5zDf2k8AI+IqE7CbgXxF58OIQG4yBb5DQZ8= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1733943177; c=relaxed/simple; bh=kdQ7Ib6f+G3Cc5oYVyNsbeJHI3RPzf1uzbuTM1qK414=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=KpShOsWMG9RUlUng2SOOeVRJHOQAzXcJYWxlZa06XoKJeocWGxCQjkirLPqtG5Lhmh43I0LvFTXVxZShzgghrpwgR14BPhwDoh3sSBQKA9mLSFlN9vTiAetkOp2TM40xqeat2ZDIr9g929DxOYTqMHgnoMteWWdzzcDphtOt7hg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=aTurvEmP; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="aTurvEmP" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 04937C4CEDE; Wed, 11 Dec 2024 18:52:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1733943176; bh=kdQ7Ib6f+G3Cc5oYVyNsbeJHI3RPzf1uzbuTM1qK414=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=aTurvEmPW+IO7zcmmDc1YJIgsaR8yCQjnVbwrK4pNqlbJnsA1ovnEuqlF7estWBvy w6/LSrL4fnwfchMVPStv6yD8wQTtBIBHUBPgyXe0VPtJtaF504biACl2c9a2+/dK8t 4lJu8MLBxTQuOSSpTBqhkYIQfjrEWEtbrmBXo/pDXZAB2tvAcHLWnZBhLGTgMG8rQh q0Ai5ZdsxChqU6+RBVeXjNmd8hLY8C+EBq69jmws+5HiqdMnRvERnHDnOU5uPrKQee /ao0RiALD0KMfq/w0qiLHjqdSurzyyCNovvzSJJ4CFZg/t+oP3ja8mfLFXaA+HNMBz 0LNGPrMa5zilw== From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Imre Deak , Lyude Paul , Sasha Levin , maarten.lankhorst@linux.intel.com, mripard@kernel.org, tzimmermann@suse.de, airlied@gmail.com, simona@ffwll.ch, jani.nikula@intel.com, harry.wentland@amd.com, alexander.deucher@amd.com, Wayne.Lin@amd.com, dri-devel@lists.freedesktop.org Subject: [PATCH AUTOSEL 6.6 19/23] drm/dp_mst: Ensure mst_primary pointer is valid in drm_dp_mst_handle_up_req() Date: Wed, 11 Dec 2024 13:51:56 -0500 Message-ID: <20241211185214.3841978-19-sashal@kernel.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20241211185214.3841978-1-sashal@kernel.org> References: <20241211185214.3841978-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore X-stable-base: Linux 6.6.65 Content-Transfer-Encoding: 8bit From: Imre Deak [ Upstream commit e54b00086f7473dbda1a7d6fc47720ced157c6a8 ] While receiving an MST up request message from one thread in drm_dp_mst_handle_up_req(), the MST topology could be removed from another thread via drm_dp_mst_topology_mgr_set_mst(false), freeing mst_primary and setting drm_dp_mst_topology_mgr::mst_primary to NULL. This could lead to a NULL deref/use-after-free of mst_primary in drm_dp_mst_handle_up_req(). Avoid the above by holding a reference for mst_primary in drm_dp_mst_handle_up_req() while it's used. v2: Fix kfreeing the request if getting an mst_primary reference fails. Cc: Lyude Paul Reviewed-by: Lyude Paul (v1) Signed-off-by: Imre Deak Link: https://patchwork.freedesktop.org/patch/msgid/20241204132007.3132494-1-imre.deak@intel.com Signed-off-by: Sasha Levin --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 24 ++++++++++++++----- 1 file changed, 18 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/display/drm_dp_mst_topology.c b/drivers/gpu/drm/display/drm_dp_mst_topology.c index 6ead31701e79e..4d954e50964f0 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3995,9 +3995,10 @@ static void drm_dp_mst_up_req_work(struct work_struct *work) static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) { struct drm_dp_pending_up_req *up_req; + struct drm_dp_mst_branch *mst_primary; if (!drm_dp_get_one_sb_msg(mgr, true, NULL)) - goto out; + goto out_clear_reply; if (!mgr->up_req_recv.have_eomt) return 0; @@ -4015,10 +4016,19 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) drm_dbg_kms(mgr->dev, "Received unknown up req type, ignoring: %x\n", up_req->msg.req_type); kfree(up_req); - goto out; + goto out_clear_reply; + } + + mutex_lock(&mgr->lock); + mst_primary = mgr->mst_primary; + if (!mst_primary || !drm_dp_mst_topology_try_get_mstb(mst_primary)) { + mutex_unlock(&mgr->lock); + kfree(up_req); + goto out_clear_reply; } + mutex_unlock(&mgr->lock); - drm_dp_send_up_ack_reply(mgr, mgr->mst_primary, up_req->msg.req_type, + drm_dp_send_up_ack_reply(mgr, mst_primary, up_req->msg.req_type, false); if (up_req->msg.req_type == DP_CONNECTION_STATUS_NOTIFY) { @@ -4035,13 +4045,13 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) conn_stat->peer_device_type); mutex_lock(&mgr->probe_lock); - handle_csn = mgr->mst_primary->link_address_sent; + handle_csn = mst_primary->link_address_sent; mutex_unlock(&mgr->probe_lock); if (!handle_csn) { drm_dbg_kms(mgr->dev, "Got CSN before finish topology probing. Skip it."); kfree(up_req); - goto out; + goto out_put_primary; } } else if (up_req->msg.req_type == DP_RESOURCE_STATUS_NOTIFY) { const struct drm_dp_resource_status_notify *res_stat = @@ -4058,7 +4068,9 @@ static int drm_dp_mst_handle_up_req(struct drm_dp_mst_topology_mgr *mgr) mutex_unlock(&mgr->up_req_lock); queue_work(system_long_wq, &mgr->up_req_work); -out: +out_put_primary: + drm_dp_mst_topology_put_mstb(mst_primary); +out_clear_reply: memset(&mgr->up_req_recv, 0, sizeof(struct drm_dp_sideband_msg_rx)); return 0; } -- 2.43.0