The patch below does not apply to the 5.15-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-5.15.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 '2025112419-scariness-motive-d737@gregkh' --subject-prefix 'PATCH 5.15.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);