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 9E43D2AE68; Mon, 30 Dec 2024 15:57:09 +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=1735574229; cv=none; b=WK8bz8LiiWPBM1PL8hDqdssfGYf0hcFD2owUfBRbP0fqZtq5nEEqYdIoK7cdA10RG2Fhx73YjgR1SKq+r/nOAYhvj8G/gn1oG8+NL8ek3Mw7p62Ntg00CGV163SOUNZzE85Zd0LrghDpOLgGAhtOPvy339znQojdnt0YYLyyviI= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1735574229; c=relaxed/simple; bh=FFYNkH4ENmZeWjKLnbtDWolT5TFb3TG5bcFLeFnvZI0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=dzqnymgVUw7bTEN6kZJkdYu6nzKaVjynO3i7NiwjduG4RGrFwc4Ad0CQe9yNatwPy8tTbHGiRRdMZ4RBGehER08MGipsXi14CUCi/U86pfqASnnwentJdbHWJBKks33uIR08sqO+eKFUIRgBxlckA6z1j6w40NBZcU6ta2KCKhc= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=E7rvSbfe; 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="E7rvSbfe" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0471AC4CED0; Mon, 30 Dec 2024 15:57:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1735574229; bh=FFYNkH4ENmZeWjKLnbtDWolT5TFb3TG5bcFLeFnvZI0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=E7rvSbfeGzHuh/O7Y5fJi815QjJdvjEWHr/Glo2pU/NAVMoYZX3N5g4H+DXThxDh+ WbAdTezrrCG+yS15W0sFMaVPjXcDXg79aKe+uaz8/2Cxy5je6rArbQv92OyU2ZiFZU j6MaGftKoeFDXflsyEyAP6TBRedfxCPFwe9mlU+Q= 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 6.12 074/114] drm/dp_mst: Ensure mst_primary pointer is valid in drm_dp_mst_handle_up_req() Date: Mon, 30 Dec 2024 16:43:11 +0100 Message-ID: <20241230154220.943187902@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241230154218.044787220@linuxfoundation.org> References: <20241230154218.044787220@linuxfoundation.org> User-Agent: quilt/0.68 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 6.12-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 bcf3a33123be..f0c6d50d8c33 100644 --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -4108,9 +4108,10 @@ 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; @@ -4128,10 +4129,19 @@ 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) { @@ -4148,13 +4158,13 @@ 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 = @@ -4171,7 +4181,9 @@ 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