FAILED: patch "[PATCH] HID: magicmouse: prevent unbounded recursion in" failed to apply to 6.1-stable tree

FAILED: patch "[PATCH] HID: magicmouse: prevent unbounded recursion in" failed to apply to 6.1-stable tree

[gregkh]

The patch below does not apply to the 6.1-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.1.y
git checkout FETCH_HEAD
git cherry-pick -x db8d634128d2ba88d79c0b601e983ebe14bb0519
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026082525-sculptor-tubeless-a928@gregkh' --subject-prefix 'PATCH 6.1.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From db8d634128d2ba88d79c0b601e983ebe14bb0519 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Jose=20Villase=C3=B1or=20Montfort?= <pepemontfort@gmail.com>
Date: Tue, 14 Jul 2026 23:35:26 -0600
Subject: [PATCH] HID: magicmouse: prevent unbounded recursion in
 magicmouse_raw_event()
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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 <pepemontfort@gmail.com>
Reviewed-by: Alec Hall <signshop.alec@gmail.com>
Tested-by: Alec Hall <signshop.alec@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index 802a3479e24b..97562765a01d 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -383,8 +383,8 @@ 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;
@@ -495,6 +495,15 @@ 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;
@@ -506,9 +515,9 @@ 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;
@@ -534,6 +543,12 @@ 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)
 {

[PATCH 6.1.y 1/2] HID: magicmouse: Prevent out-of-bounds (OOB) read during DOUBLE_REPORT_ID

[Sasha Levin]

From: Lee Jones <lee@kernel.org>

[ Upstream commit d93ba918a185aca2594da63e92fdc5495b559c0f ]

It is currently possible for a malicious or misconfigured USB device to
cause an out-of-bounds (OOB) read when submitting reports using
DOUBLE_REPORT_ID by specifying a large report length and providing a
smaller one.

Let's prevent that by comparing the specified report length with the
actual size of the data read in from userspace.  If the actual data
length ends up being smaller than specified, we'll politely warn the
user and prevent any further processing.

Signed-off-by: Lee Jones <lee@kernel.org>
Reviewed-by: Günther Noack <gnoack@google.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Stable-dep-of: db8d634128d2 ("HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event()")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/hid/hid-magicmouse.c | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/drivers/hid/hid-magicmouse.c b/drivers/hid/hid-magicmouse.c
index d5df2745f3da4..de13f4ec5dfd4 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -384,6 +384,10 @@ static int magicmouse_raw_event(struct hid_device *hdev,
 	struct input_dev *input = msc->input;
 	int x = 0, y = 0, ii, clicks = 0, npoints;
 
+	/* Protect against zero sized recursive calls from DOUBLE_REPORT_ID */
+	if (size < 1)
+		return 0;
+
 	switch (data[0]) {
 	case TRACKPAD_REPORT_ID:
 	case TRACKPAD2_BT_REPORT_ID:
@@ -484,6 +488,18 @@ static int magicmouse_raw_event(struct hid_device *hdev,
 		/* Sometimes the trackpad sends two touch reports in one
 		 * packet.
 		 */
+
+		/* Ensure that we have at least 2 elements (report type and size) */
+		if (size < 2)
+			return 0;
+
+		if (size < data[1] + 2) {
+			hid_warn(hdev,
+				 "received report length (%d) was smaller than specified (%d)",
+				 size, data[1] + 2);
+			return 0;
+		}
+
 		magicmouse_raw_event(hdev, report, data + 2, data[1]);
 		magicmouse_raw_event(hdev, report, data + 2 + data[1],
 			size - 2 - data[1]);
-- 
2.53.0

[PATCH 6.1.y 2/2] HID: magicmouse: prevent unbounded recursion in magicmouse_raw_event()

[Sasha Levin]

From: Jose Villaseñor Montfort <pepemontfort@gmail.com>

[ 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 <pepemontfort@gmail.com>
Reviewed-by: Alec Hall <signshop.alec@gmail.com>
Tested-by: Alec Hall <signshop.alec@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 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 de13f4ec5dfd4..31cea46dee903 100644
--- a/drivers/hid/hid-magicmouse.c
+++ b/drivers/hid/hid-magicmouse.c
@@ -377,8 +377,8 @@ 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;
@@ -489,6 +489,15 @@ 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;
@@ -500,9 +509,9 @@ 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;
@@ -527,6 +536,12 @@ 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