[PATCH v3 3/3] quota: Add more checking after reading from quota file

[Zhihao Cheng <chengzhihao1@huawei.com>]

It would be better to do more sanity checking (eg. dqdh_entries,
block no.) for the content read from quota file, which can prevent
corrupting the quota file.

Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
---
 fs/quota/quota_tree.c | 19 +++++++++++++++++--
 1 file changed, 17 insertions(+), 2 deletions(-)

diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index 0fa73ca28045..0f1493e0f6d0 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -96,6 +96,11 @@ static int check_dquot_block_header(struct qtree_mem_dqinfo *info,
 	err = do_check_range(info->dqi_sb, "dqdh_prev_free",
 			     le32_to_cpu(dh->dqdh_prev_free), 0,
 			     info->dqi_blocks - 1);
+	if (err)
+		return err;
+	err = do_check_range(info->dqi_sb, "dqdh_entries",
+			     le16_to_cpu(dh->dqdh_entries), 0,
+			     qtree_dqstr_in_blk(info));
 
 	return err;
 }
@@ -348,6 +353,10 @@ static int do_insert_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 	}
 	ref = (__le32 *)buf;
 	newblk = le32_to_cpu(ref[get_index(info, dquot->dq_id, depth)]);
+	ret = do_check_range(dquot->dq_sb, "block", newblk, 0,
+			     info->dqi_blocks - 1);
+	if (ret)
+		goto out_buf;
 	if (!newblk)
 		newson = 1;
 	if (depth == info->dqi_qtree_depth - 1) {
@@ -739,15 +748,21 @@ static int find_next_id(struct qtree_mem_dqinfo *info, qid_t *id,
 		goto out_buf;
 	}
 	for (i = __get_index(info, *id, depth); i < epb; i++) {
-		if (ref[i] == cpu_to_le32(0)) {
+		uint blk_no = le32_to_cpu(ref[i]);
+
+		if (blk_no == 0) {
 			*id += level_inc;
 			continue;
 		}
+		ret = do_check_range(info->dqi_sb, "block", blk_no, 0,
+				     info->dqi_blocks - 1);
+		if (ret)
+			goto out_buf;
 		if (depth == info->dqi_qtree_depth - 1) {
 			ret = 0;
 			goto out_buf;
 		}
-		ret = find_next_id(info, id, le32_to_cpu(ref[i]), depth + 1);
+		ret = find_next_id(info, id, blk_no, depth + 1);
 		if (ret != -ENOENT)
 			break;
 	}
-- 
2.31.1