linux-kernel - [PATCH AUTOSEL 6.12 08/36] udf: Skip parent dir link count update if corrupted

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Message-ID: <20241211185028.3841047-8-sashal@kernel.org>
Date: Wed, 11 Dec 2024 13:49:24 -0500
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: Jan Kara <jack@...e.cz>,
	Sasha Levin <sashal@...nel.org>,
	jack@...e.com
Subject: [PATCH AUTOSEL 6.12 08/36] udf: Skip parent dir link count update if corrupted

From: Jan Kara <jack@...e.cz>

[ Upstream commit c5566903af56dd1abb092f18dcb0c770d6cd8dcb ]

If the parent directory link count is too low (likely directory inode
corruption), just skip updating its link count as if it goes to 0 too
early it can cause unexpected issues.

Signed-off-by: Jan Kara <jack@...e.cz>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/udf/namei.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/fs/udf/namei.c b/fs/udf/namei.c
index 78a603129dd58..2be775d30ac10 100644
--- a/fs/udf/namei.c
+++ b/fs/udf/namei.c
@@ -517,7 +517,11 @@ static int udf_rmdir(struct inode *dir, struct dentry *dentry)
 			 inode->i_nlink);
 	clear_nlink(inode);
 	inode->i_size = 0;
-	inode_dec_link_count(dir);
+	if (dir->i_nlink >= 3)
+		inode_dec_link_count(dir);
+	else
+		udf_warn(inode->i_sb, "parent dir link count too low (%u)\n",
+			 dir->i_nlink);
 	udf_add_fid_counter(dir->i_sb, true, -1);
 	inode_set_mtime_to_ts(dir,
 			      inode_set_ctime_to_ts(dir, inode_set_ctime_current(inode)));
-- 
2.43.0