Commit 8ecb790e authored by Theodore Ts'o's avatar Theodore Ts'o
Browse files

ext4: avoid potential buffer over-read in parse_apply_sb_mount_options() 



Unlike other strings in the ext4 superblock, we rely on tune2fs to
make sure s_mount_opts is NUL terminated.  Harden
parse_apply_sb_mount_options() by treating s_mount_opts as a potential
__nonstring.

Cc: stable@vger.kernel.org
Fixes: 8b67f04a ("ext4: Add mount options in superblock")
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Reviewed-by: default avatarDarrick J. Wong <djwong@kernel.org>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Message-ID: <20250916-tune2fs-v2-1-d594dc7486f0@mit.edu>
Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent 12e803c8

fs/ext4/super.c

+5 −12
Original line number Diff line number Diff line
@@ -2469,7 +2469,7 @@ static int parse_apply_sb_mount_options(struct super_block *sb, 
					struct ext4_fs_context *m_ctx)

{

	struct ext4_sb_info *sbi = EXT4_SB(sb);

	char *s_mount_opts = NULL;

	char s_mount_opts[65];

	struct ext4_fs_context *s_ctx = NULL;

	struct fs_context *fc = NULL;

	int ret = -ENOMEM;
@@ -2477,15 +2477,11 @@ static int parse_apply_sb_mount_options(struct super_block *sb, 
	if (!sbi->s_es->s_mount_opts[0])

		return 0;



	s_mount_opts = kstrndup(sbi->s_es->s_mount_opts,

				sizeof(sbi->s_es->s_mount_opts),

				GFP_KERNEL);

	if (!s_mount_opts)

		return ret;

	strscpy_pad(s_mount_opts, sbi->s_es->s_mount_opts);



	fc = kzalloc(sizeof(struct fs_context), GFP_KERNEL);

	if (!fc)

		goto out_free;

		return -ENOMEM;



	s_ctx = kzalloc(sizeof(struct ext4_fs_context), GFP_KERNEL);

	if (!s_ctx)
@@ -2517,11 +2513,8 @@ static int parse_apply_sb_mount_options(struct super_block *sb, 
	ret = 0;



out_free:

	if (fc) {

	ext4_fc_free(fc);

	kfree(fc);

	}

	kfree(s_mount_opts);

	return ret;

}