[PATCH 4.9 051/207] quota: check block number when reading the block in quota file

[Greg Kroah-Hartman]

From: Zhang Yi <yi.zhang@xxxxxxxxxx>

commit 9bf3d20331295b1ecb81f4ed9ef358c51699a050 upstream.

The block number in the quota tree on disk should be smaller than the
v2_disk_dqinfo.dqi_blocks. If the quota file was corrupted, we may be
allocating an 'allocated' block and that would lead to a loop in a tree,
which will probably trigger oops later. This patch adds a check for the
block number in the quota tree to prevent such potential issue.

Link: https://lore.kernel.org/r/20211008093821.1001186-2-yi.zhang@xxxxxxxxxx
Signed-off-by: Zhang Yi <yi.zhang@xxxxxxxxxx>
Cc: stable@xxxxxxxxxx
Signed-off-by: Jan Kara <jack@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 fs/quota/quota_tree.c |   14 ++++++++++++++
 1 file changed, 14 insertions(+)

--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -487,6 +487,13 @@ static int remove_tree(struct qtree_mem_
 		goto out_buf;
 	}
 	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
+	if (newblk < QT_TREEOFF || newblk >= info->dqi_blocks) {
+		quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
+			    newblk, info->dqi_blocks);
+		ret = -EUCLEAN;
+		goto out_buf;
+	}
+
 	if (depth == info->dqi_qtree_depth - 1) {
 		ret = free_dqentry(info, dquot, newblk);
 		newblk = 0;
@@ -586,6 +593,13 @@ static loff_t find_tree_dqentry(struct q
 	blk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
 	if (!blk)	/* No reference? */
 		goto out_buf;
+	if (blk < QT_TREEOFF || blk >= info->dqi_blocks) {
+		quota_error(dquot->dq_sb, "Getting block too big (%u >= %u)",
+			    blk, info->dqi_blocks);
+		ret = -EUCLEAN;
+		goto out_buf;
+	}
+
 	if (depth < info->dqi_qtree_depth - 1)
 		ret = find_tree_dqentry(info, dquot, blk, depth+1);
 	else