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ext4: init error handle resource before init group descriptors

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Now, 's_err_report' timer is init after ext4_group_desc_init() when fill
super. Theoretically, ext4_group_desc_init() may access to error handle
as follows:
__ext4_fill_super
  ext4_group_desc_init
    ext4_check_descriptors
      ext4_get_group_desc
        ext4_error
          ext4_handle_error
            ext4_commit_super
              ext4_update_super
                if (!es->s_error_count)
                  mod_timer(&sbi->s_err_report, jiffies + 24*60*60*HZ);
		  --> Accessing Uninitialized Variables
timer_setup(&sbi->s_err_report, print_daily_error_info, 0);

Maybe above issue is just theoretical, as ext4_check_descriptors() didn't
judge 'gpd' which get from ext4_get_group_desc(), if access to error handle
ext4_get_group_desc() will return NULL, then will trigger null-ptr-deref in
ext4_check_descriptors().
However, from the perspective of pure code, it is better to initialize
resource that may need to be used first.

Signed-off-by: Ye Bin <yebin10@huawei.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230119013711.86680-1-yebin@huaweicloud.com
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
This commit is contained in:
Ye Bin
2023-01-19 09:37:11 +08:00
committed by Theodore Ts'o
parent 0f7bfd6f81
commit 172e344e6f
1 changed files with 7 additions and 12 deletions
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19
fs/ext4/super.c
View File

@@ -4738,7 +4738,6 @@ static int ext4_group_desc_init(struct super_block *sb,
struct ext4_sb_info *sbi = EXT4_SB(sb);
unsigned int db_count;
ext4_fsblk_t block;
int ret;
int i;
db_count = (sbi->s_groups_count + EXT4_DESC_PER_BLOCK(sb) - 1) /
@@ -4778,8 +4777,7 @@ static int ext4_group_desc_init(struct super_block *sb,
ext4_msg(sb, KERN_ERR,
"can't read group descriptor %d", i);
sbi->s_gdb_count = i;
ret = PTR_ERR(bh);
goto out;
return PTR_ERR(bh);
}
rcu_read_lock();
rcu_dereference(sbi->s_group_desc)[i] = bh;
@@ -4788,13 +4786,10 @@ static int ext4_group_desc_init(struct super_block *sb,
sbi->s_gdb_count = db_count;
if (!ext4_check_descriptors(sb, logical_sb_block, first_not_zeroed)) {
ext4_msg(sb, KERN_ERR, "group descriptors corrupted!");
ret = -EFSCORRUPTED;
goto out;
return -EFSCORRUPTED;
}
return 0;
out:
ext4_group_desc_free(sbi);
return ret;
}
static int ext4_load_and_init_journal(struct super_block *sb,
@@ -5220,14 +5215,14 @@ static int __ext4_fill_super(struct fs_context *fc, struct super_block *sb)
if (ext4_geometry_check(sb, es))
goto failed_mount;
err = ext4_group_desc_init(sb, es, logical_sb_block, &first_not_zeroed);
if (err)
goto failed_mount;
timer_setup(&sbi->s_err_report, print_daily_error_info, 0);
spin_lock_init(&sbi->s_error_lock);
INIT_WORK(&sbi->s_error_work, flush_stashed_error_work);
err = ext4_group_desc_init(sb, es, logical_sb_block, &first_not_zeroed);
if (err)
goto failed_mount3;
/* Register extent status tree shrinker */
if (ext4_es_register_shrinker(sbi))
goto failed_mount3;