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 EE752542813; Mon, 31 Aug 2026 13:45:59 +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=1788183962; cv=none; b=lm+0nWxPscL6VH9Wona+RYgarLHZ60nW/kipq3Qy9yN1e0qmHzc0aR0aqJEdSsQeyIimCp2KXa2X3FZzs4HsJ+mqdg2QIEd6z17VIo+YFjjYo0FOhnHTGZL0IgwAXvwDhihAGuN8Kmi/rt8YgDaChShF7rNuBfUBnViogXKLeUM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788183962; c=relaxed/simple; bh=7BpGfKca3NYpnGSo7IWpSMvTN8UNyPTH2WqEXaZbGGc=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version:Content-Type; b=lnmhwMVRivmdUYxFKrYEsCaqjGI/qWqO/n0YnmFT+FNB4iHjlJqcvcEYttpW4H8/kKeqVebfzxO+sHy8bieq5Ow5+NLNyxj9dilqiIRkB6IGoU4Ip9Gn9hij10SA9GI9UdNI4t9neK7vGP6fIe4ieP6lYXdFxY59nOY9RJsSJAs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=eEfn+8Vi; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="eEfn+8Vi" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 21ED51F00A3D; Mon, 31 Aug 2026 13:45:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788183959; bh=xvwVtcfnqgdX5D0SXtgSnEeY6yCu23bt3+lc5v1meMQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=eEfn+8Vid3rMbIwmRWcbhgW4CNV744Hk3slIWVEWU+36ecZEYzDSMBJvK0UX98abK wzSeoMP+En+v1/x1yXLiFBthYpUzgnog8iRnzZ9bJMdH1I1Zau1PJI41yGHndKrO9R 3xPtecDaesraB67VoSw0fovtT9kyEAZzokl9zaTU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, =?UTF-8?q?Jose=20Villase=C3=B1or=20Montfort?= , Alec Hall , Jiri Kosina , Sasha Levin Subject: [PATCH 6.18 24/83] HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event() Date: Mon, 31 Aug 2026 15:34:00 +0200 Message-ID: <20260831133400.501540318@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260831133359.207714926@linuxfoundation.org> References: <20260831133359.207714926@linuxfoundation.org> User-Agent: quilt/0.69 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-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ 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 Signed-off-by: Greg Kroah-Hartman --- drivers/hid/hid-magicmouse.c | 25 ++++++++++++++++++++----- 1 file changed, 20 insertions(+), 5 deletions(-) --- a/drivers/hid/hid-magicmouse.c +++ b/drivers/hid/hid-magicmouse.c @@ -383,8 +383,8 @@ static void magicmouse_emit_touch(struct } } -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; @@ -495,6 +495,15 @@ static int magicmouse_raw_event(struct h * 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; @@ -506,9 +515,9 @@ static int magicmouse_raw_event(struct h 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; @@ -534,6 +543,12 @@ static int magicmouse_raw_event(struct h 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) {