Fix NULL dereference in umem.c

Fix NULL dereference in umem.c

Signed-off-by: Neil Brown <neilb@suse.de>
Tested-by: Dave Chinner <dgc@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 1 deletions

diff --git a/drivers/block/umem.c b/drivers/block/umem.c
index 99806f9ee4ce..5f5095afb06b 100644
--- a/drivers/block/umem.c
+++ b/drivers/block/umem.c
@@ -484,7 +484,8 @@ static void process_page(unsigned long data)
                 page->idx++;
                 if (page->idx >= bio->bi_vcnt) {
                         page->bio = bio->bi_next;
-                        page->idx = page->bio->bi_idx;
+                        if (page->bio)
+                                page->idx = page->bio->bi_idx;
                 }
 
                 pci_unmap_page(card->dev, desc->data_dma_handle,