On 08/06/2012 11:17 AM, Alex Elder wrote:
Add checks on the validity of the snap_count and snap_names_len
field values in rbd_dev_ondisk_valid(). This eliminates the
need to do them in rbd_header_from_disk().
Signed-off-by: Alex Elder <elder@xxxxxxxxxxx>
Just a small typo below. Looks good otherwise:
Reviewed-by: Josh Durgin <josh.durgin@xxxxxxxxxxx>
---
drivers/block/rbd.c | 36 +++++++++++++++++++++++++++---------
1 file changed, 27 insertions(+), 9 deletions(-)
Index: b/drivers/block/rbd.c
===================================================================
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -482,8 +482,31 @@ static void rbd_coll_release(struct kref
static bool rbd_dev_ondisk_valid(struct rbd_image_header_ondisk *ondisk)
{
- return !memcmp(&ondisk->text,
- RBD_HEADER_TEXT, sizeof (RBD_HEADER_TEXT));
+ size_t size;
+ u32 snap_count;
+
+ /* The header has to start with the magic rbd header text */
+ if (memcmp(&ondisk->text, RBD_HEADER_TEXT, sizeof (RBD_HEADER_TEXT)))
+ return false;
+
+ /*
+ * The size of a snapshot header has to fit in a size_t, and
+ * that valid limits the number of snapshots.
typo
+ */
+ snap_count = le32_to_cpu(ondisk->snap_count);
+ size = SIZE_MAX - sizeof (struct ceph_snap_context);
+ if (snap_count > size / sizeof (__le64))
+ return false;
+
+ /*
+ * Not only that, but the size of the entire the snapshot
+ * header must also be representable in a size_t.
+ */
+ size -= snap_count * sizeof (__le64);
+ if ((u64) size < le64_to_cpu(ondisk->snap_names_len))
+ return false;
+
+ return true;
}
/*
@@ -500,15 +523,10 @@ static int rbd_header_from_disk(struct r
if (!rbd_dev_ondisk_valid(ondisk))
return -ENXIO;
- snap_count = le32_to_cpu(ondisk->snap_count);
-
- /* Make sure we don't overflow below */
- size = SIZE_MAX - sizeof (struct ceph_snap_context);
- if (snap_count > size / sizeof (header->snapc->snaps[0]))
- return -EINVAL;
-
memset(header, 0, sizeof (*header));
+ snap_count = le32_to_cpu(ondisk->snap_count);
+
size = sizeof (ondisk->block_name) + 1;
header->object_prefix = kmalloc(size, GFP_KERNEL);
if (!header->object_prefix)
--
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