FAILED: patch "[PATCH] Input: pegasus-notetaker - fix potential out-of-bounds access" failed to apply to 5.10-stable tree

[<gregkh@linuxfoundation.org>]

The patch below does not apply to the 5.10-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-5.10.y
git checkout FETCH_HEAD
git cherry-pick -x 69aeb507312306f73495598a055293fa749d454e
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2025112420-cleaver-backlight-0d73@gregkh' --subject-prefix 'PATCH 5.10.y' HEAD^..

Possible dependencies:



thanks,

greg k-h

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

From 69aeb507312306f73495598a055293fa749d454e Mon Sep 17 00:00:00 2001
From: Seungjin Bae <eeodqql09@gmail.com>
Date: Fri, 17 Oct 2025 15:36:31 -0700
Subject: [PATCH] Input: pegasus-notetaker - fix potential out-of-bounds access

In the pegasus_notetaker driver, the pegasus_probe() function allocates
the URB transfer buffer using the wMaxPacketSize value from
the endpoint descriptor. An attacker can use a malicious USB descriptor
to force the allocation of a very small buffer.

Subsequently, if the device sends an interrupt packet with a specific
pattern (e.g., where the first byte is 0x80 or 0x42),
the pegasus_parse_packet() function parses the packet without checking
the allocated buffer size. This leads to an out-of-bounds memory access.

Fixes: 1afca2b66aac ("Input: add Pegasus Notetaker tablet driver")
Signed-off-by: Seungjin Bae <eeodqql09@gmail.com>
Link: https://lore.kernel.org/r/20251007214131.3737115-2-eeodqql09@gmail.com
Cc: stable@vger.kernel.org
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>

diff --git a/drivers/input/tablet/pegasus_notetaker.c b/drivers/input/tablet/pegasus_notetaker.c
index 8d6b71d59793..eabb4a0b8a0d 100644
--- a/drivers/input/tablet/pegasus_notetaker.c
+++ b/drivers/input/tablet/pegasus_notetaker.c
@@ -63,6 +63,9 @@
 #define BUTTON_PRESSED			0xb5
 #define COMMAND_VERSION			0xa9
 
+/* 1 Status + 1 Color + 2 X + 2 Y = 6 bytes */
+#define NOTETAKER_PACKET_SIZE		6
+
 /* in xy data packet */
 #define BATTERY_NO_REPORT		0x40
 #define BATTERY_LOW			0x41
@@ -311,6 +314,12 @@ static int pegasus_probe(struct usb_interface *intf,
 	}
 
 	pegasus->data_len = usb_maxpacket(dev, pipe);
+	if (pegasus->data_len < NOTETAKER_PACKET_SIZE) {
+		dev_err(&intf->dev, "packet size is too small (%d)\n",
+			pegasus->data_len);
+		error = -EINVAL;
+		goto err_free_mem;
+	}
 
 	pegasus->data = usb_alloc_coherent(dev, pegasus->data_len, GFP_KERNEL,
 					   &pegasus->data_dma);