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rbd: expand rbd_dev_ondisk_valid() checks 

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@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
This commit is contained in:
Alex Elder 2012-08-02 11:29:45 -05:00
parent 28cb775de1
commit 103a150f0c
1 changed files with 27 additions and 9 deletions
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36
drivers/block/rbd.c
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@ -481,8 +481,31 @@ static void rbd_coll_release(struct kref *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 limits the number of snapshots.
*/
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;
}
/*
@ -499,15 +522,10 @@ static int rbd_header_from_disk(struct rbd_image_header *header,
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)