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ext2: Add more validity checks for inode counts

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Add checks verifying number of inodes stored in the superblock matches
the number computed from number of inodes per group. Also verify we have
at least one block worth of inodes per group. This prevents crashes on
corrupted filesystems.

Reported-by: syzbot+d273f7d7f58afd93be48@syzkaller.appspotmail.com
Signed-off-by: Jan Kara <jack@suse.cz>
This commit is contained in:
Jan Kara 2022-07-26 13:13:50 +02:00
parent bd6e21a904
commit fa78f33693
1 changed files with 10 additions and 2 deletions
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12
fs/ext2/super.c
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@ -1059,9 +1059,10 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_frags_per_group);
goto failed_mount;
}
if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
if (sbi->s_inodes_per_group < sbi->s_inodes_per_block ||
sbi->s_inodes_per_group > sb->s_blocksize * 8) {
ext2_msg(sb, KERN_ERR,
"error: #inodes per group too big: %lu",
"error: invalid #inodes per group: %lu",
sbi->s_inodes_per_group);
goto failed_mount;
}
@ -1071,6 +1072,13 @@ static int ext2_fill_super(struct super_block *sb, void *data, int silent)
sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
le32_to_cpu(es->s_first_data_block) - 1)
/ EXT2_BLOCKS_PER_GROUP(sb)) + 1;
if ((u64)sbi->s_groups_count * sbi->s_inodes_per_group !=
le32_to_cpu(es->s_inodes_count)) {
ext2_msg(sb, KERN_ERR, "error: invalid #inodes: %u vs computed %llu",
le32_to_cpu(es->s_inodes_count),
(u64)sbi->s_groups_count * sbi->s_inodes_per_group);
goto failed_mount;
}
db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
EXT2_DESC_PER_BLOCK(sb);
sbi->s_group_desc = kmalloc_array(db_count,