Commit 1d6a7f4e authored by Baokun Li's avatar Baokun Li Committed by Yifan Qiao
Browse files

ext4: avoid overflow when setting values via sysfs 

mainline inclusion
from mainline-v6.10-rc1
commit 9e8e819f8f272c4e5dcd0bd6c7450e36481ed139
category: bugfix
bugzilla: https://gitee.com/src-openeuler/kernel/issues/IAD018
CVE: CVE-2024-40955

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9e8e819f8f272c4e5dcd0bd6c7450e36481ed139



--------------------------------

When setting values of type unsigned int through sysfs, we use kstrtoul()
to parse it and then truncate part of it as the final set value, when the
set value is greater than UINT_MAX, the set value will not match what we
see because of the truncation. As follows:

  $ echo 4294967296 > /sys/fs/ext4/sda/mb_max_linear_groups
  $ cat /sys/fs/ext4/sda/mb_max_linear_groups
    0

So we use kstrtouint() to parse the attr_pointer_ui type to avoid the
inconsistency described above. In addition, a judgment is added to avoid
setting s_resv_clusters less than 0.

Signed-off-by: default avatarBaokun Li <libaokun1@huawei.com>
Reviewed-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20240319113325.3110393-2-libaokun1@huawei.com


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarYifan Qiao <qiaoyifan4@huawei.com>
parent e027f52d

fs/ext4/sysfs.c

+6 −5
Original line number Diff line number Diff line
@@ -104,7 +104,7 @@ static ssize_t reserved_clusters_store(struct ext4_sb_info *sbi, 
	int ret;



	ret = kstrtoull(skip_spaces(buf), 0, &val);

	if (ret || val >= clusters)

	if (ret || val >= clusters || (s64)val < 0)

		return -EINVAL;



	atomic64_set(&sbi->s_resv_clusters, val);
@@ -451,7 +451,8 @@ static ssize_t ext4_attr_store(struct kobject *kobj, 
						s_kobj);

	struct ext4_attr *a = container_of(attr, struct ext4_attr, attr);

	void *ptr = calc_ptr(a, sbi);

	unsigned long t;

	unsigned int t;

	unsigned long lt;

	int ret;



	switch (a->attr_id) {
@@ -460,7 +461,7 @@ static ssize_t ext4_attr_store(struct kobject *kobj, 
	case attr_pointer_ui:

		if (!ptr)

			return 0;

		ret = kstrtoul(skip_spaces(buf), 0, &t);

		ret = kstrtouint(skip_spaces(buf), 0, &t);

		if (ret)

			return ret;

		if (a->attr_ptr == ptr_ext4_super_block_offset)
@@ -471,10 +472,10 @@ static ssize_t ext4_attr_store(struct kobject *kobj, 
	case attr_pointer_ul:

		if (!ptr)

			return 0;

		ret = kstrtoul(skip_spaces(buf), 0, &t);

		ret = kstrtoul(skip_spaces(buf), 0, &lt);

		if (ret)

			return ret;

		*((unsigned long *) ptr) = t;

		*((unsigned long *) ptr) = lt;

		return len;

	case attr_inode_readahead:

		return inode_readahead_blks_store(sbi, buf, len);