crush: fix a bug in tree bucket decode

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

Cc: stable@vger.kernel.org
Signed-off-by: Ilya Dryomov <idryomov@gmail.com>
Reviewed-by: Josh Durgin <jdurgin@redhat.com>

diff --git a/net/ceph/osdmap.c b/net/ceph/osdmap.c
index 1579669..4a31258 100644 (file)
--- a/net/ceph/osdmap.c
+++ b/net/ceph/osdmap.c
@@ -89,7 +89,7 @@ static int crush_decode_tree_bucket(void **p, void *end,
 {
        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;