[PATCH 6.6 223/301] firewire: nosy: ensure user_length is taken into account when fetching packet contents

Greg Kroah-Hartman
2024-05-14T11:21:07Z

From: Thanassis Avgerinos <thanassis.avgerinos@gmail.com>

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>
---
drivers/firewire/nosy.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/firewire/nosy.c
+++ b/drivers/firewire/nosy.c
@@ -148,10 +148,12 @@ packet_buffer_get(struct client *client,
if (atomic_read(&buffer->size) == 0)
return -ENODEV;

- /* FIXME: Check length <= user_length. */
+ length = buffer->head->length;
+
+ if (length > user_length)
+ return 0;

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

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