From 67f34f093c0f7bf33f5b4ae64d3d695a3b978285 Mon Sep 17 00:00:00 2001 From: Thanassis Avgerinos Date: Wed, 17 Apr 2024 11:30:02 -0400 Subject: [PATCH] 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 Signed-off-by: Takashi Sakamoto Signed-off-by: Greg Kroah-Hartman --- drivers/firewire/nosy.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/firewire/nosy.c b/drivers/firewire/nosy.c index ac85e03e88e1..f3784c054dd6 100644 --- a/drivers/firewire/nosy.c +++ b/drivers/firewire/nosy.c @@ -161,10 +161,12 @@ packet_buffer_get(struct client *client, char __user *data, size_t user_length) 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))