On Wed 18-10-23 19:42:18, Baokun Li wrote:
> The maximum value of flexbg_size is 2^31, but the maximum value of int
> is (2^31 - 1), so overflow may occur when the type of flexbg_size is
> declared as int.
>
> For example, when uninit_mask is initialized in ext4_alloc_group_tables(),
> if flexbg_size == 2^31, the initialized uninit_mask is incorrect, and this
> may causes set_flexbg_block_bitmap() to trigger a BUG_ON().
>
> Therefore, the flexbg_size type is declared as unsigned int to avoid
> overflow and memory waste.
>
> Signed-off-by: Baokun Li <libaokun1@xxxxxxxxxx>
Looks good. Feel free to add:
Reviewed-by: Jan Kara <jack@xxxxxxx>
Honza
> ---
> fs/ext4/resize.c | 13 +++++++------
> 1 file changed, 7 insertions(+), 6 deletions(-)
>
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index 4fe061edefdd..c6d4539d4c1f 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -228,7 +228,7 @@ struct ext4_new_flex_group_data {
> *
> * Returns NULL on failure otherwise address of the allocated structure.
> */
> -static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned long flexbg_size)
> +static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size)
> {
> struct ext4_new_flex_group_data *flex_gd;
>
> @@ -283,7 +283,7 @@ static void free_flex_gd(struct ext4_new_flex_group_data *flex_gd)
> */
> static int ext4_alloc_group_tables(struct super_block *sb,
> struct ext4_new_flex_group_data *flex_gd,
> - int flexbg_size)
> + unsigned int flexbg_size)
> {
> struct ext4_new_group_data *group_data = flex_gd->groups;
> ext4_fsblk_t start_blk;
> @@ -384,12 +384,12 @@ static int ext4_alloc_group_tables(struct super_block *sb,
> group = group_data[0].group;
>
> printk(KERN_DEBUG "EXT4-fs: adding a flex group with "
> - "%d groups, flexbg size is %d:\n", flex_gd->count,
> + "%u groups, flexbg size is %u:\n", flex_gd->count,
> flexbg_size);
>
> for (i = 0; i < flex_gd->count; i++) {
> ext4_debug(
> - "adding %s group %u: %u blocks (%d free, %d mdata blocks)\n",
> + "adding %s group %u: %u blocks (%u free, %u mdata blocks)\n",
> ext4_bg_has_super(sb, group + i) ? "normal" :
> "no-super", group + i,
> group_data[i].blocks_count,
> @@ -1606,7 +1606,7 @@ static int ext4_flex_group_add(struct super_block *sb,
> static int ext4_setup_next_flex_gd(struct super_block *sb,
> struct ext4_new_flex_group_data *flex_gd,
> ext4_fsblk_t n_blocks_count,
> - unsigned long flexbg_size)
> + unsigned int flexbg_size)
> {
> struct ext4_sb_info *sbi = EXT4_SB(sb);
> struct ext4_super_block *es = sbi->s_es;
> @@ -1990,8 +1990,9 @@ int ext4_resize_fs(struct super_block *sb, ext4_fsblk_t n_blocks_count)
> ext4_fsblk_t o_blocks_count;
> ext4_fsblk_t n_blocks_count_retry = 0;
> unsigned long last_update_time = 0;
> - int err = 0, flexbg_size = 1 << sbi->s_log_groups_per_flex;
> + int err = 0;
> int meta_bg;
> + unsigned int flexbg_size = ext4_flex_bg_size(sbi);
>
> /* See if the device is actually as big as what was requested */
> bh = ext4_sb_bread(sb, n_blocks_count - 1, 0);
> --
> 2.31.1
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
