From 9bf3d20331295b1ecb81f4ed9ef358c51699a050 Mon Sep 17 00:00:00 2001
From: Zhang Yi <yi.zhang@huawei.com>
Date: Fri, 8 Oct 2021 17:38:20 +0800
Subject: [PATCH] quota: check block number when reading the block in quota
 file
Git-commit: 9bf3d20331295b1ecb81f4ed9ef358c51699a050
Patch-mainline: v5.16-rc1
References: bsc#1197366 CVE-2021-45868

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@huawei.com
Signed-off-by: Zhang Yi <yi.zhang@huawei.com>
Cc: stable@kernel.org
Signed-off-by: Jan Kara <jack@suse.cz>
Acked-by: Vasant Karasulli <vkarasulli@suse.de>

---
 fs/quota/quota_tree.c | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/fs/quota/quota_tree.c b/fs/quota/quota_tree.c
index d3e995e1046f..583b7f7715f9 100644
--- a/fs/quota/quota_tree.c
+++ b/fs/quota/quota_tree.c
@@ -479,6 +479,13 @@ static int remove_tree(struct qtree_mem_dqinfo *info, struct dquot *dquot,
 		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;
@@ -578,6 +585,13 @@ static loff_t find_tree_dqentry(struct qtree_mem_dqinfo *info,
 	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
--
2.32.0