Commit 7b8c7bd2 authored Apr 17, 2024 by Thanassis Avgerinos Committed by Greg Kroah-Hartman May 17, 2024

firewire: nosy: ensure user_length is taken into account when fetching packet contents

commit 38762a0763c10c24a4915feee722d7aa6e73eb98 upstream.

Ensure that packet_buffer_get respects the user_length provided. If
the length of the head packet exceeds the user_length, packet_buffer_get
will now return 0 to signify to the user that no data were read
and a larger buffer size is required. Helps prevent user space overflows.

Signed-off-by: Thanassis Avgerinos <thanassis.avgerinos@gmail.com>
Signed-off-by: Takashi Sakamoto <o-takashi@sakamocchi.jp>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

parent e44d4063

drivers/firewire/nosy.c

+4 −2

Original line number	Original line	Diff line number	Diff line
	@@ -148,10 +148,12 @@ packet_buffer_get(struct client client, char __user data, size_t user_length)
	if (atomic_read(&buffer->size) == 0)		if (atomic_read(&buffer->size) == 0)
	return -ENODEV;		return -ENODEV;

	/* FIXME: Check length <= user_length. */		length = buffer->head->length;

			if (length > user_length)
			return 0;

	end = buffer->data + buffer->capacity;		end = buffer->data + buffer->capacity;
	length = buffer->head->length;

	if (&buffer->head->data[length] < end) {		if (&buffer->head->data[length] < end) {
	if (copy_to_user(data, buffer->head->data, length))		if (copy_to_user(data, buffer->head->data, length))