4.4-stable review patch. If anyone has any objections, please let me know.
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From: Liu Bo bo.li.liu@oracle.com
commit 3eb548ee3a8042d95ad81be254e67a5222c24e03 upstream.
During updating btree, we could push items between sibling nodes/leaves, for leaves data sections starts reversely from the end of the block while for nodes we only have key pairs which are stored one by one from the start of the block.
So we could do try to push key pairs from one node to the next node right in the tree, and after that, we update the node's nritems to reflect the correct end while leaving the stale content in the node. One may intentionally corrupt the fs image and access the stale content by bumping the nritems and causes various crashes.
This takes the in-memory @nritems as the correct one and gets to memset the unused part of a btree node.
Signed-off-by: Liu Bo bo.li.liu@oracle.com Reviewed-by: David Sterba dsterba@suse.com Signed-off-by: David Sterba dsterba@suse.com Signed-off-by: Ben Hutchings ben.hutchings@codethink.co.uk Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/btrfs/extent_io.c | 11 +++++++++++ 1 file changed, 11 insertions(+)
--- a/fs/btrfs/extent_io.c +++ b/fs/btrfs/extent_io.c @@ -3858,6 +3858,17 @@ static noinline_for_stack int write_one_ if (btrfs_header_owner(eb) == BTRFS_TREE_LOG_OBJECTID) bio_flags = EXTENT_BIO_TREE_LOG;
+ /* set btree node beyond nritems with 0 to avoid stale content */ + if (btrfs_header_level(eb) > 0) { + u32 nritems; + unsigned long end; + + nritems = btrfs_header_nritems(eb); + end = btrfs_node_key_ptr_offset(nritems); + + memset_extent_buffer(eb, 0, end, eb->len - end); + } + for (i = 0; i < num_pages; i++) { struct page *p = eb->pages[i];