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 CC13121504F; Thu, 12 Dec 2024 15:12:25 +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=1734016345; cv=none; b=abZ8MfAMG0xu+1UG089Rx5PrcQtQCYd1wRwT2CkxcXYRM+D7QiqNu6bHfirfvruf+o5BLJatoTBam2V8VqzT/Y38MvnNDSxq+2L2eD2BzzQ2pQbebtGQ0SJwToMArXSjEUD7zdDMJQYkerxWmWRCcJfI8dP6wrY/eXYXnBbWVIA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1734016345; c=relaxed/simple; bh=9KMvNZLpUOnEb1L7qM0Ur3nbPKbVntKMsJpnQID33EQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=RxPzY7EdCrYhuxuuCpEmPKxAzx5gKIhjZs49aFhsW7yWDu9wTKbhuwlwhDDyhahwO5pVqb+5YSN6RF9A3mQU0Bl18AEvdl+8SxIgoo7zOs+EiXRoq+7DE7DNMzhThXvTOjUCSoy/TWKiZOpsC3B4rx1D8CKEdlkcApnpArO7aLI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=h/VyiUhy; 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="h/VyiUhy" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 30992C4CEE1; Thu, 12 Dec 2024 15:12:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1734016345; bh=9KMvNZLpUOnEb1L7qM0Ur3nbPKbVntKMsJpnQID33EQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=h/VyiUhyKVSNXezW180Y7U1T6DaHSBJhp0ikqtdmO+SXzqpxKUDqxde176WV+Imf1 iJQIsTcFsoflhQqHWoWPaWCTZYQqpFKwtjloGzLgMALYdMJQgcspWQBKOmEOq8jyhG 822FyGhTdgbhJHI9Le+rL1G9KsaA9OaLERixQhkc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Lyude Paul , Imre Deak Subject: [PATCH 6.12 173/466] drm/dp_mst: Fix resetting msg rx state after topology removal Date: Thu, 12 Dec 2024 15:55:42 +0100 Message-ID: <20241212144313.635214754@linuxfoundation.org> X-Mailer: git-send-email 2.47.1 In-Reply-To: <20241212144306.641051666@linuxfoundation.org> References: <20241212144306.641051666@linuxfoundation.org> User-Agent: quilt/0.67 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Imre Deak commit a6fa67d26de385c3c7a23c1e109a0e23bfda4ec7 upstream. If the MST topology is removed during the reception of an MST down reply or MST up request sideband message, the drm_dp_mst_topology_mgr::up_req_recv/down_rep_recv states could be reset from one thread via drm_dp_mst_topology_mgr_set_mst(false), racing with the reading/parsing of the message from another thread via drm_dp_mst_handle_down_rep() or drm_dp_mst_handle_up_req(). The race is possible since the reader/parser doesn't hold any lock while accessing the reception state. This in turn can lead to a memory corruption in the reader/parser as described by commit bd2fccac61b4 ("drm/dp_mst: Fix MST sideband message body length check"). Fix the above by resetting the message reception state if needed before reading/parsing a message. Another solution would be to hold the drm_dp_mst_topology_mgr::lock for the whole duration of the message reception/parsing in drm_dp_mst_handle_down_rep() and drm_dp_mst_handle_up_req(), however this would require a bigger change. Since the fix is also needed for stable, opting for the simpler solution in this patch. Cc: Lyude Paul Cc: Fixes: 1d082618bbf3 ("drm/display/dp_mst: Fix down/up message handling after sink disconnect") Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/13056 Reviewed-by: Lyude Paul Signed-off-by: Imre Deak Link: https://patchwork.freedesktop.org/patch/msgid/20241203160223.2926014-2-imre.deak@intel.com Signed-off-by: Greg Kroah-Hartman --- drivers/gpu/drm/display/drm_dp_mst_topology.c | 21 +++++++++++++++++++-- include/drm/display/drm_dp_mst_helper.h | 7 +++++++ 2 files changed, 26 insertions(+), 2 deletions(-) --- a/drivers/gpu/drm/display/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/display/drm_dp_mst_topology.c @@ -3700,8 +3700,7 @@ int drm_dp_mst_topology_mgr_set_mst(stru ret = 0; mgr->payload_id_table_cleared = false; - memset(&mgr->down_rep_recv, 0, sizeof(mgr->down_rep_recv)); - memset(&mgr->up_req_recv, 0, sizeof(mgr->up_req_recv)); + mgr->reset_rx_state = true; } out_unlock: @@ -3859,6 +3858,11 @@ out_fail: } EXPORT_SYMBOL(drm_dp_mst_topology_mgr_resume); +static void reset_msg_rx_state(struct drm_dp_sideband_msg_rx *msg) +{ + memset(msg, 0, sizeof(*msg)); +} + static bool drm_dp_get_one_sb_msg(struct drm_dp_mst_topology_mgr *mgr, bool up, struct drm_dp_mst_branch **mstb) @@ -4172,6 +4176,17 @@ out: return 0; } +static void update_msg_rx_state(struct drm_dp_mst_topology_mgr *mgr) +{ + mutex_lock(&mgr->lock); + if (mgr->reset_rx_state) { + mgr->reset_rx_state = false; + reset_msg_rx_state(&mgr->down_rep_recv); + reset_msg_rx_state(&mgr->up_req_recv); + } + mutex_unlock(&mgr->lock); +} + /** * drm_dp_mst_hpd_irq_handle_event() - MST hotplug IRQ handle MST event * @mgr: manager to notify irq for. @@ -4206,6 +4221,8 @@ int drm_dp_mst_hpd_irq_handle_event(stru *handled = true; } + update_msg_rx_state(mgr); + if (esi[1] & DP_DOWN_REP_MSG_RDY) { ret = drm_dp_mst_handle_down_rep(mgr); *handled = true; --- a/include/drm/display/drm_dp_mst_helper.h +++ b/include/drm/display/drm_dp_mst_helper.h @@ -700,6 +700,13 @@ struct drm_dp_mst_topology_mgr { bool payload_id_table_cleared : 1; /** + * @reset_rx_state: The down request's reply and up request message + * receiver state must be reset, after the topology manager got + * removed. Protected by @lock. + */ + bool reset_rx_state : 1; + + /** * @payload_count: The number of currently active payloads in hardware. This value is only * intended to be used internally by MST helpers for payload tracking, and is only safe to * read/write from the atomic commit (not check) context.