[PATCH 3.2 056/110] crush: fix a bug in tree bucket decode

[Ben Hutchings]

3.2.71-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Ilya Dryomov <idryomov@xxxxxxxxx>

commit 82cd003a77173c91b9acad8033fb7931dac8d751 upstream.

struct crush_bucket_tree::num_nodes is u8, so ceph_decode_8_safe()
should be used.  -Wconversion catches this, but I guess it went
unnoticed in all the noise it spews.  The actual problem (at least for
common crushmaps) isn't the u32 -> u8 truncation though - it's the
advancement by 4 bytes instead of 1 in the crushmap buffer.

Fixes: http://tracker.ceph.com/issues/2759

Signed-off-by: Ilya Dryomov <idryomov@xxxxxxxxx>
Reviewed-by: Josh Durgin <jdurgin@xxxxxxxxxx>
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
---
 net/ceph/osdmap.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -102,7 +102,7 @@ static int crush_decode_tree_bucket(void
 {
 	int j;
 	dout("crush_decode_tree_bucket %p to %p\n", *p, end);
-	ceph_decode_32_safe(p, end, b->num_nodes, bad);
+	ceph_decode_8_safe(p, end, b->num_nodes, bad);
 	b->node_weights = kcalloc(b->num_nodes, sizeof(u32), GFP_NOFS);
 	if (b->node_weights == NULL)
 		return -ENOMEM;

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