firewire: ohci: handle receive packets with a data length of zero

Queueing to receive an ISO packet with a payload length of zero
silently does nothing in dualbuffer mode, and crashes the kernel in
packet-per-buffer mode.  Return an error in dualbuffer mode, because
the DMA controller won't let us do what we want, and work correctly in
packet-per-buffer mode.

Signed-off-by: Jay Fenlason <fenlason@redhat.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Cc: stable@kernel.org

1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index a71477541dc7..553c74e1e4e3 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -2189,6 +2189,13 @@ static int ohci_queue_iso_receive_dualbuffer(struct fw_iso_context *base,
         page     = payload >> PAGE_SHIFT;
         offset   = payload & ~PAGE_MASK;
         rest     = p->payload_length;
+        /*
+         * The controllers I've tested have not worked correctly when
+         * second_req_count is zero.  Rather than do something we know won't
+         * work, return an error
+         */
+        if (rest == 0)
+                return -EINVAL;
 
         /* FIXME: make packet-per-buffer/dual-buffer a context option */
         while (rest > 0) {
@@ -2242,7 +2249,7 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
                                         unsigned long payload)
 {
         struct iso_context *ctx = container_of(base, struct iso_context, base);
-        struct descriptor *d = NULL, *pd = NULL;
+        struct descriptor *d, *pd;
         struct fw_iso_packet *p = packet;
         dma_addr_t d_bus, page_bus;
         u32 z, header_z, rest;
@@ -2280,8 +2287,9 @@ static int ohci_queue_iso_receive_packet_per_buffer(struct fw_iso_context *base,
                 d->data_address = cpu_to_le32(d_bus + (z * sizeof(*d)));
 
                 rest = payload_per_buffer;
+                pd = d;
                 for (j = 1; j < z; j++) {
-                        pd = d + j;
+                        pd++;
                         pd->control = cpu_to_le16(DESCRIPTOR_STATUS |
                                                   DESCRIPTOR_INPUT_MORE);