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>
(cherry picked from commit 67f34f093c0f7bf33f5b4ae64d3d695a3b978285)
Signed-off-by: Vegard Nossum <vegard.nossum@oracle.com>
diff --git a/drivers/firewire/nosy.c b/drivers/firewire/nosy.c
index 646dca0..3f7c1c5 100644
--- a/drivers/firewire/nosy.c
+++ b/drivers/firewire/nosy.c
@@ -161,10 +161,12 @@
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))