linux-kernel - [PATCH 1/2] f2fs: Constrain the modification range of dir

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Date: Fri, 22 Dec 2023 11:29:00 +0800
From: Yongpeng Yang <yangyongpeng1@...o.com>
To: Jaegeuk Kim <jaegeuk@...nel.org>,
	Chao Yu <chao@...nel.org>
Cc: linux-f2fs-devel@...ts.sourceforge.net,
	linux-kernel@...r.kernel.org,
	Yongpeng Yang <yangyongpeng1@...o.com>
Subject: [PATCH 1/2] f2fs: Constrain the modification range of dir_level in the sysfs

The {struct f2fs_sb_info}->dir_level can be modified through the sysfs
interface, but its value range is not limited. If the value exceeds
MAX_DIR_HASH_DEPTH and the mount options include "noinline_dentry",
the following error will occur:
[root@...ora ~]# mount -o noinline_dentry /dev/sdb  /mnt/sdb/
[root@...ora ~]# echo 128 > /sys/fs/f2fs/sdb/dir_level
[root@...ora ~]# cd /mnt/sdb/
[root@...ora sdb]# mkdir test
[root@...ora sdb]# cd test/
[root@...ora test]# mkdir test
mkdir: cannot create directory 'test': Argument list too long

Signed-off-by: Yongpeng Yang <yangyongpeng1@...o.com>
---
 fs/f2fs/sysfs.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/fs/f2fs/sysfs.c b/fs/f2fs/sysfs.c
index 7099ffa57299..8c8424b05fc7 100644
--- a/fs/f2fs/sysfs.c
+++ b/fs/f2fs/sysfs.c
@@ -741,6 +741,13 @@ static ssize_t __sbi_store(struct f2fs_attr *a,
 		return count;
 	}

+	if (!strcmp(a->attr.name, "dir_level")) {
+		if (t > MAX_DIR_HASH_DEPTH)
+			return -EINVAL;
+		sbi->dir_level = t;
+		return count;
+	}
+
 	*ui = (unsigned int)t;

 	return count;
-- 
2.40.1