[PATCH 3.16 030/245] Btrfs: check btree node's nritems

Ben Hutchings
2020-04-23T23:24:43Z

From: Liu Bo <bo.li.liu@oracle.com>

commit 053ab70f0604224c7893b43f9d9d5efa283580d6 upstream.

When btree node (level = 1) has nritems which equals to zero,
we can end up with panic due to insert_ptr()'s

BUG_ON(slot > nritems);

where slot is 1 and nritems is 0, as copy_for_split() calls
insert_ptr(.., path->slots[1] + 1, ...);

A invalid value results in the whole mess, this adds the check
for btree's node nritems so that we stop reading block when
when something is wrong.

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: Chris Mason <clm@fb.com>
Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
---
fs/btrfs/disk-io.c | 16 ++++++++++++++++
1 file changed, 16 insertions(+)

--- a/fs/btrfs/disk-io.c
+++ b/fs/btrfs/disk-io.c
@@ -594,6 +594,19 @@ static noinline int check_leaf(struct bt
return 0;
}

+static int check_node(struct btrfs_root *root, struct extent_buffer *node)
+{
+ unsigned long nr = btrfs_header_nritems(node);
+
+ if (nr == 0 || nr > BTRFS_NODEPTRS_PER_BLOCK(root)) {
+ btrfs_crit(root->fs_info,
+ "corrupt node: block %llu root %llu nritems %lu",
+ node->start, root->objectid, nr);
+ return -EIO;
+ }
+ return 0;
+}
+
static int btree_readpage_end_io_hook(struct btrfs_io_bio *io_bio,
u64 phy_offset, struct page *page,
u64 start, u64 end, int mirror)
@@ -666,6 +679,9 @@ static int btree_readpage_end_io_hook(st
ret = -EIO;
}

+ if (found_level > 0 && check_node(root, eb))
+ ret = -EIO;
+
if (!ret)
set_extent_buffer_uptodate(eb);