Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6

* 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
  firewire: ohci: fix race when reading count in AR descriptor
  firewire: ohci: avoid reallocation of AR buffers
  firewire: ohci: fix race in AR split packet handling
  firewire: ohci: fix buffer overflow in AR split packet handling

1 files changed, 65 insertions, 23 deletions

diff --git a/drivers/firewire/ohci.c b/drivers/firewire/ohci.c
index 9dcb17d51aee..84eb607d6c03 100644
--- a/drivers/firewire/ohci.c
+++ b/drivers/firewire/ohci.c
@@ -577,17 +577,11 @@ static int ohci_update_phy_reg(struct fw_card *card, int addr,
         return ret;
 }
 
-static int ar_context_add_page(struct ar_context *ctx)
+static void ar_context_link_page(struct ar_context *ctx,
+                                 struct ar_buffer *ab, dma_addr_t ab_bus)
 {
-        struct device *dev = ctx->ohci->card.device;
-        struct ar_buffer *ab;
-        dma_addr_t uninitialized_var(ab_bus);
         size_t offset;
 
-        ab = dma_alloc_coherent(dev, PAGE_SIZE, &ab_bus, GFP_ATOMIC);
-        if (ab == NULL)
-                return -ENOMEM;
-
         ab->next = NULL;
         memset(&ab->descriptor, 0, sizeof(ab->descriptor));
         ab->descriptor.control        = cpu_to_le16(DESCRIPTOR_INPUT_MORE |
@@ -606,6 +600,19 @@ static int ar_context_add_page(struct ar_context *ctx)
 
         reg_write(ctx->ohci, CONTROL_SET(ctx->regs), CONTEXT_WAKE);
         flush_writes(ctx->ohci);
+}
+
+static int ar_context_add_page(struct ar_context *ctx)
+{
+        struct device *dev = ctx->ohci->card.device;
+        struct ar_buffer *ab;
+        dma_addr_t uninitialized_var(ab_bus);
+
+        ab = dma_alloc_coherent(dev, PAGE_SIZE, &ab_bus, GFP_ATOMIC);
+        if (ab == NULL)
+                return -ENOMEM;
+
+        ar_context_link_page(ctx, ab, ab_bus);
 
         return 0;
 }
@@ -730,16 +737,17 @@ static __le32 *handle_ar_packet(struct ar_context *ctx, __le32 *buffer)
 static void ar_context_tasklet(unsigned long data)
 {
         struct ar_context *ctx = (struct ar_context *)data;
-        struct fw_ohci *ohci = ctx->ohci;
         struct ar_buffer *ab;
         struct descriptor *d;
         void *buffer, *end;
+        __le16 res_count;
 
         ab = ctx->current_buffer;
         d = &ab->descriptor;
 
-        if (d->res_count == 0) {
-                size_t size, rest, offset;
+        res_count = ACCESS_ONCE(d->res_count);
+        if (res_count == 0) {
+                size_t size, size2, rest, pktsize, size3, offset;
                 dma_addr_t start_bus;
                 void *start;
 
@@ -750,29 +758,63 @@ static void ar_context_tasklet(unsigned long data)
                  */
 
                 offset = offsetof(struct ar_buffer, data);
-                start = buffer = ab;
+                start = ab;
                 start_bus = le32_to_cpu(ab->descriptor.data_address) - offset;
+                buffer = ab->data;
 
                 ab = ab->next;
                 d = &ab->descriptor;
-                size = buffer + PAGE_SIZE - ctx->pointer;
+                size = start + PAGE_SIZE - ctx->pointer;
+                /* valid buffer data in the next page */
                 rest = le16_to_cpu(d->req_count) - le16_to_cpu(d->res_count);
+                /* what actually fits in this page */
+                size2 = min(rest, (size_t)PAGE_SIZE - offset - size);
                 memmove(buffer, ctx->pointer, size);
-                memcpy(buffer + size, ab->data, rest);
-                ctx->current_buffer = ab;
-                ctx->pointer = (void *) ab->data + rest;
-                end = buffer + size + rest;
+                memcpy(buffer + size, ab->data, size2);
+
+                while (size > 0) {
+                        void *next = handle_ar_packet(ctx, buffer);
+                        pktsize = next - buffer;
+                        if (pktsize >= size) {
+                                /*
+                                 * We have handled all the data that was
+                                 * originally in this page, so we can now
+                                 * continue in the next page.
+                                 */
+                                buffer = next;
+                                break;
+                        }
+                        /* move the next packet to the start of the buffer */
+                        memmove(buffer, next, size + size2 - pktsize);
+                        size -= pktsize;
+                        /* fill up this page again */
+                        size3 = min(rest - size2,
+                                    (size_t)PAGE_SIZE - offset - size - size2);
+                        memcpy(buffer + size + size2,
+                               (void *) ab->data + size2, size3);
+                        size2 += size3;
+                }
 
-                while (buffer < end)
-                        buffer = handle_ar_packet(ctx, buffer);
+                if (rest > 0) {
+                        /* handle the packets that are fully in the next page */
+                        buffer = (void *) ab->data +
+                                        (buffer - (start + offset + size));
+                        end = (void *) ab->data + rest;
+
+                        while (buffer < end)
+                                buffer = handle_ar_packet(ctx, buffer);
 
-                dma_free_coherent(ohci->card.device, PAGE_SIZE,
-                                  start, start_bus);
-                ar_context_add_page(ctx);
+                        ctx->current_buffer = ab;
+                        ctx->pointer = end;
+
+                        ar_context_link_page(ctx, start, start_bus);
+                } else {
+                        ctx->pointer = start + PAGE_SIZE;
+                }
         } else {
                 buffer = ctx->pointer;
                 ctx->pointer = end =
-                        (void *) ab + PAGE_SIZE - le16_to_cpu(d->res_count);
+                        (void *) ab + PAGE_SIZE - le16_to_cpu(res_count);
 
                 while (buffer < end)
                         buffer = handle_ar_packet(ctx, buffer);