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 627EB1AC891; Mon, 30 Dec 2024 15:46:20 +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=1735573580; cv=none; b=CouElEKPF7YppT3dsygugq7fn0epejIKSjnlfRQ8PKdBH6u2dcqxKY6K3/1VsheOjNFgsFooT15H7HCP0zCekevFvlLkrajtnlbahPaYhlsnKfAQdghTKuXCSZoTkcYceA3s0MECIfzW199hNW1zoGNiG8rkDmwfAWbZvJxlaHg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735573580; c=relaxed/simple; bh=nV44cRgjE2+98HA9KlA+Om+492YJ7/a4IAc2Uj7D/DI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=oOSUSwbLNCY3YrI7S3BS9o5L7IGZdzwERW2pZ/+V7W8MZ9vvktttivH6Q32VVA/kjxqauZLV7TIjQMTII+vHHcKIFOaHMvUt1/jLmsgjv6qpcVEsW1aWCNF/1xfuC7HN5orV04uYEaqW+m1i9rSnWUf8tZ++gc6CblUUuzFyBNQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=INn6Eosp; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="INn6Eosp" Received: by smtp.kernel.org (Postfix) with ESMTPSA id D5E48C4CED0; Mon, 30 Dec 2024 15:46:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1735573580; bh=nV44cRgjE2+98HA9KlA+Om+492YJ7/a4IAc2Uj7D/DI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=INn6EospemlKRhalcsehKn5dNGlsiIBGUC8ik47Ay0SGAe6o9lh0dJ4FH+DN7bIDR lIR+PT+YgJUpj9obPLrFVk8MTtc1LKs8vJT7PPYzvdv/3ApGh/VJl7Jr4LheMcsR/R NUQ6EhNK49zpN0cVAgEyv1Nc6qd/j4EU+5SXry2c= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lyude Paul , Imre Deak , Sasha Levin Subject: [PATCH 6.1 36/60] drm/dp_mst: Ensure mst_primary pointer is valid in drm_dp_mst_handle_up_req() Date: Mon, 30 Dec 2024 16:42:46 +0100 Message-ID: <20241230154208.651587698@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241230154207.276570972@linuxfoundation.org> References: <20241230154207.276570972@linuxfoundation.org> User-Agent: quilt/0.68 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org 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: 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 4f8fcfaa80fd..d8cbb4eadc5b 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -4033,9 +4033,10 @@ 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; @@ -4053,10 +4054,19 @@ 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) { @@ -4073,13 +4083,13 @@ 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 = @@ -4096,7 +4106,9 @@ 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; } -- 2.39.5