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=1794325332; b=eCohNW1VgBIsmDBAG0E57bmNyaHxOCjIUN3RLnlcFvFB/fIwgLSjn+lHbNlSTl1m05ee gJSKDf4Jt69URyhJc2dT95gticQEKT3DGvlDTJawkwf0j/WLq/MqokE2GpJh+B44D8ef6 AJQr7QrSy+5D4T1HCF7Lwy/Zyard9Jzl0zzEuGVLav5k6sBQ/ctGMTZILCqHxZHRa3nlN ubtE+HUDL8PWu5IdgU5BOaYp/n8cV7bBcShX9VUGqKv8VEMt6bhbEoKm4LG7VkB16sRDs TT9qLfMOhGk3PlVoL29newNpbK1FJ3An+PqwmtiLup3JMeVrWNBOygJbBXE9aN+VYOA== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794325332; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:MIME-Version:Content-Transfer-Encoding; bh=x+4vLy+9USPKTI8mun5204dpIrEL4Ku81mbzIxZDywM=; b=NAD/dQ0KrdR3ynZywNtAc7KSTGnlu5msv9wdOH+GaaxIxoUsVT6kNCYHyrMGdyqoj7Oc sx4Pcd2hP4oiymdVJ1EHxW/5NmHuaVEeHmwqJaFUYdFsxHKg3DEUSmckKnmsSmfVs9ImN +TUbndVt0eD3mvl+6ngtRgDnA55oOyh+kkQ9bOihZIwtgZyI/RroLfzzS2jaRKRaZD2+7 fChD2bRCiP5yIannKdmjIcQFD9APNoax+VwITjxi7m7LCkJ56vEOfIrWzRseFKP5PQX/q CCHGftO9h3a4USSdmO700jQUe5+zcmp20oN65CUoZnXRTz/oJa7wg/vIr8jSGvhafhw== 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="UhiHyDb/"; 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 900B7606C401 for ; Tue, 10 Nov 2026 15:42:12 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=UhiHyDb/ Received: by smtp.kernel.org (Postfix) with ESMTPSA id 726641F008A1; Tue, 10 Nov 2026 15:42:11 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794325332; bh=x+4vLy+9USPKTI8mun5204dpIrEL4Ku81mbzIxZDywM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=UhiHyDb/PeCaDVJGu4kTY5tTMdF0fSfW/70Tp08OqA/7Qy5ORBeMNUL8Ly5rYyHu0 pkpIRveB1oX9Yqznu3p1RkZZCQH/t+WtIh5JmE1+KKL9VqxLVUKAYUAtpCngWse865 QFOaDelFqYN913CIEJ+L8u6ovS/i/6g2T+A1FrirEmYhNbSvR4874XWQHtRuTcu3ka Y8FKLTnZXz1pT1a4xg/Z1b+9Cmvy3U1YhxnGkioPnkdtsV7YfyY9/PluFj3f1g0xKk f6HK/z/QJ5geALkgI8ONcBzKWZYUi8eq801B0syfTRb7VbgrOc1uNh90y5W05ZE2vR jlf4zysNR9OAQ== From: Sasha Levin To: stable@vger.kernel.org Cc: Seungjin Bae , stable , Nathan Rebello , Heikki Krogerus , Greg Kroah-Hartman , Sasha Levin Subject: [PATCH 5.15.y] usb: typec: ucsi: ccg: Validate altmode index in GET_CURRENT_CAM response Date: Tue, 10 Nov 2026 10:42:10 -0500 Message-ID: <20261110154146.2333804-1-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20261107060407-failed-5.15-02ee864e8d21@kernel.org> References: <20261107060407-failed-5.15-02ee864e8d21@kernel.org> X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Seungjin Bae [ Upstream commit 02ee864e8d2142c5648998944c3306ea6a763c26 ] When the PPM reports more than one DisplayPort alternate mode for a connector, ucsi_ccg_update_altmodes() merges them into a single entry in uc->updated[] and sets uc->has_multiple_dp. In that case, ucsi_ccg_update_get_current_cam_cmd() rewrites the response of the GET_CURRENT_CAM command. The response is a single byte holding the index of the currently active alternate mode, and it is provided by the PPM firmware. The function uses this byte directly as an index into uc->orig[], and then uses the linked_idx read from that entry as the translated index into uc->updated[]. Both arrays have UCSI_MAX_ALTMODES entries, but neither index is checked against that size. If a malicious or buggy PPM reports a value of UCSI_MAX_ALTMODES or larger, e.g. 0xFF, uc->orig[cam].linked_idx reads over the end of uc->orig[]. The byte read from there is then used as the index for writing cam into uc->updated[new_cam].active_idx, so the out-of-bounds read is followed by an out-of-bounds write. This happens without any userspace action, since the UCSI core issues GET_CURRENT_CAM on its own when handling connector changes. Fix this by rejecting responses whose index is out of range, printing an error and returning -EPROTO, so that the caller cannot accept this. Also check linked_idx before using it as an index, so that the write into uc->updated[] is always within bounds. The response is now only processed when the command completed without an error. ucsi_sync_control_common() only reads the response when the CCI reports command completion, so otherwise the buffer is not filled and must not be mistaken for an invalid index. This bug was found with a Python script that traces where firmware input is used. Fixes: 170a6726d0e2 ("usb: typec: ucsi: add support for separate DP altmode devices") Cc: stable Reported-by: Nathan Rebello Assisted-by: LLM Signed-off-by: Seungjin Bae Reviewed-by: Heikki Krogerus Link: https://patch.msgid.link/20261003215520.611083-2-eeodqql09@gmail.com Signed-off-by: Greg Kroah-Hartman [ sashal: adapted GET_CURRENT_CAM error handling to ucsi_ccg_read() without the upstream CCI status checks ] Signed-off-by: Sasha Levin --- drivers/usb/typec/ucsi/ucsi_ccg.c | 18 ++++++++++++++++-- 1 file changed, 16 insertions(+), 2 deletions(-) diff --git a/drivers/usb/typec/ucsi/ucsi_ccg.c b/drivers/usb/typec/ucsi/ucsi_ccg.c index b50933cd4babf..2caef7d02cbb6 100644 --- a/drivers/usb/typec/ucsi/ucsi_ccg.c +++ b/drivers/usb/typec/ucsi/ucsi_ccg.c @@ -351,14 +351,28 @@ static int ucsi_ccg_init(struct ucsi_ccg *uc) return -ETIMEDOUT; } -static void ucsi_ccg_update_get_current_cam_cmd(struct ucsi_ccg *uc, u8 *data) +static int ucsi_ccg_update_get_current_cam_cmd(struct ucsi_ccg *uc, u8 *data) { u8 cam, new_cam; cam = data[0]; + if (cam >= UCSI_MAX_ALTMODES) { + dev_err(uc->dev, "PPM returned invalid alternate mode index %u\n", + cam); + return -EPROTO; + } + new_cam = uc->orig[cam].linked_idx; + if (new_cam >= UCSI_MAX_ALTMODES) { + dev_err(uc->dev, "invalid linked alternate mode index %u for %u\n", + new_cam, cam); + return -EPROTO; + } + uc->updated[new_cam].active_idx = cam; data[0] = new_cam; + + return 0; } static bool ucsi_ccg_update_altmodes(struct ucsi *ucsi, @@ -541,7 +555,7 @@ static int ucsi_ccg_read(struct ucsi *ucsi, unsigned int offset, switch (UCSI_COMMAND(uc->last_cmd_sent)) { case UCSI_GET_CURRENT_CAM: if (uc->has_multiple_dp) - ucsi_ccg_update_get_current_cam_cmd(uc, (u8 *)val); + ret = ucsi_ccg_update_get_current_cam_cmd(uc, (u8 *)val); break; case UCSI_GET_ALTERNATE_MODES: if (UCSI_ALTMODE_RECIPIENT(uc->last_cmd_sent) == -- 2.53.0