From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 16FF93C2BA4 for ; Wed, 26 Aug 2026 13:11:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787749884; cv=none; b=GJdafXpAT9P+GjRHebfK5WSeAq+ymZ1D/C4vIM1m73VPTgg/0wZnTq+2YhLZvXDEvNUlBMkuRPw0BdZhGU25rV5/YMd/8nXC9HxfKsIMM33NQ13t3F37DQUqaldEhJa7wlJsZRI++dAVAFhcCjZuHn5MKb0+o2tjjvgj72oTlog= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1787749884; c=relaxed/simple; bh=hDJ5utMxynrQhpxEw04mx/UVUa5b22tXo2jjob7Q5u8=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=JTJ5scfkjYdtQP/2RB+BDhkZSkTzcQ9cCnKp8CxJ+aFl6x+huk7NEfOgKIu/opRo/z9KcLdddNetDo7t2mfsVxKohcrAKPBRd2qzGiFruRTv+1AXG90/WdeBe1o0CFX+3/3KE3gFB2/vK8csoaRPZP6ofdwHlK5NN7LvBRbPigA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=P1BzLy0U; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="P1BzLy0U" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 22E441F00A3D; Wed, 26 Aug 2026 13:11:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1787749882; bh=ZhSAsh08zX2PgmKorY1o2j2OnxAggYmFvaVkBJLwUv4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=P1BzLy0Ux4/2p4CW4bF86Y2tiO8F8o3OW6iQJxyMarUF2eH1g/IdKJoHORpTa4z/K Pgnz/meXj3cPCSl2h9cXYOL8z7IaMOg5/e4TP/vhyNWt/b9IPltAYO9nHFfc82OmRq 5gvKs6TNNWJI+vAy+zotixahLIx1SNn2MtMtR0RoTEHMHsi9QYfQ2ojb1YJ0whUK4p vX/xelHWptU0ZZwoIpmGlGDAiTrIKEYsJbFYB0xIqXDp9fvdhtySD3tAFqscGwFVCc VISqKsjdvLvqNs3NvzC46Iqlftjn2uqpiwuacQrYID3rXjGKgm54v71pnn2IiOSOfr 0LlM9t52X/RIA== From: Sasha Levin To: stable@vger.kernel.org Cc: =?UTF-8?q?Jose=20Villase=C3=B1or=20Montfort?= , Alec Hall , Jiri Kosina , Sasha Levin Subject: [PATCH 5.15.y 2/2] HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() Date: Wed, 26 Aug 2026 09:11:19 -0400 Message-ID: <20260826131119.3036540-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260826131119.3036540-1-sashal@kernel.org> References: <2026082526-status-turbine-ec0a@gregkh> <20260826131119.3036540-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Jose Villaseñor Montfort [ Upstream commit db8d634128d2ba88d79c0b601e983ebe14bb0519 ] magicmouse_raw_event() handles DOUBLE_REPORT_ID (0xf7) packets, which pack two touch reports into one, by splitting the packet and calling itself on each half. The only guard against runaway recursion is a "size < 1" check, which stops zero-sized calls but does not bound the recursion depth. A malicious HID device that matches this driver can send a report starting with DOUBLE_REPORT_ID and filled with the sequence [0xf7, 0x00]. Each level consumes two bytes and recurses on the remainder, so an incoming report of up to HID_MAX_BUFFER_SIZE (16 KiB) drives roughly 8000 nested calls. That easily exhausts the 16 KiB kernel stack, leading to a stack overflow: a panic with CONFIG_VMAP_STACK, or memory corruption without it. A double report only ever wraps two normal reports; it is never legitimately nested. Refuse to re-enter the DOUBLE_REPORT_ID case from a recursive call so the recursion depth is bounded to two, while all valid packets keep being parsed exactly as before. Fixes: a462230e16ac ("HID: magicmouse: enable Magic Trackpad support") Link: https://lore.kernel.org/linux-input/20260706181347.700DB1F00A3F@smtp.kernel.org/ Cc: stable@vger.kernel.org Signed-off-by: Jose Villaseñor Montfort Reviewed-by: Alec Hall Tested-by: Alec Hall Signed-off-by: Jiri Kosina Signed-off-by: Sasha Levin --- drivers/hid/hid-magicmouse.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c index a459fc62cb739..cf8a10752f4c8 100644 --- a/drivers/hid/hid-magicmouse.c +++ b/drivers/hid/hid-magicmouse.c @@ -368,8 +368,8 @@ static void magicmouse_emit_touch(struct magicmouse_sc *msc, int raw_id, u8 *tda } } -static int magicmouse_raw_event(struct hid_device *hdev, - struct hid_report *report, u8 *data, int size) +static int __magicmouse_raw_event(struct hid_device *hdev, + struct hid_report *report, u8 *data, int size, bool nested) { struct magicmouse_sc *msc = hid_get_drvdata(hdev); struct input_dev *input = msc->input; @@ -480,6 +480,15 @@ static int magicmouse_raw_event(struct hid_device *hdev, * packet. */ + /* + * A double report only ever wraps two normal reports, so it is + * never nested. Refuse to recurse a second time; otherwise a + * malicious device could chain DOUBLE_REPORT_ID packets to drive + * unbounded recursion and overflow the kernel stack. + */ + if (nested) + return 0; + /* Ensure that we have at least 2 elements (report type and size) */ if (size < 2) return 0; @@ -491,9 +500,9 @@ static int magicmouse_raw_event(struct hid_device *hdev, return 0; } - magicmouse_raw_event(hdev, report, data + 2, data[1]); - magicmouse_raw_event(hdev, report, data + 2 + data[1], - size - 2 - data[1]); + __magicmouse_raw_event(hdev, report, data + 2, data[1], true); + __magicmouse_raw_event(hdev, report, data + 2 + data[1], + size - 2 - data[1], true); return 0; default: return 0; @@ -516,6 +525,12 @@ static int magicmouse_raw_event(struct hid_device *hdev, return 1; } +static int magicmouse_raw_event(struct hid_device *hdev, + struct hid_report *report, u8 *data, int size) +{ + return __magicmouse_raw_event(hdev, report, data, size, false); +} + static int magicmouse_event(struct hid_device *hdev, struct hid_field *field, struct hid_usage *usage, __s32 value) { -- 2.53.0