[PATCH OLK-6.6 1/2] ext4: avoid overflow when setting values via sysfs

From: Baokun Li libaokun1@huawei.com

stable inclusion from stable-v6.9.7 commit 87a11878e5273cbf2a99dda0fce4119238e10dc5 category: bugfix bugzilla: https://gitee.com/src-openeuler/kernel/issues/IACZZP CVE: CVE-2024-40971

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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commit 9e8e819f8f272c4e5dcd0bd6c7450e36481ed139 upstream.

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: Baokun Li libaokun1@huawei.com Reviewed-by: Jan Kara jack@suse.cz Link: https://lore.kernel.org/r/20240319113325.3110393-2-libaokun1@huawei.com Signed-off-by: Theodore Ts'o tytso@mit.edu Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org Signed-off-by: Yifan Qiao qiaoyifan4@huawei.com --- fs/ext4/sysfs.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-)

diff --git a/fs/ext4/sysfs.c b/fs/ext4/sysfs.c index 6d332dff79dd..ca820620b974 100644 --- a/fs/ext4/sysfs.c +++ b/fs/ext4/sysfs.c @@ -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);