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ext4: don't allow overlapping system zones

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commit bf9a379d09 upstream.

Currently, add_system_zone() just silently merges two added system zones
that overlap. However the overlap should not happen and it generally
suggests that some unrelated metadata overlap which indicates the fs is
corrupted. We should have caught such problems earlier (e.g. in
ext4_check_descriptors()) but add this check as another line of defense.
In later patch we also use this for stricter checking of journal inode
extent tree.

Reviewed-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200728130437.7804-3-jack@suse.cz
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jan Kara
2021-03-17 17:44:13 +01:00
committed by Greg Kroah-Hartman
parent d01b5fc061
commit f175d63724
1 changed files with 12 additions and 22 deletions
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34
fs/ext4/block_validity.c
View File

@@ -57,7 +57,7 @@ static int add_system_zone(struct ext4_sb_info *sbi,
ext4_fsblk_t start_blk,
unsigned int count)
{
struct ext4_system_zone *new_entry = NULL, *entry;
struct ext4_system_zone *new_entry, *entry;
struct rb_node **n = &sbi->system_blks.rb_node, *node;
struct rb_node *parent = NULL, *new_node = NULL;
@@ -68,30 +68,20 @@ static int add_system_zone(struct ext4_sb_info *sbi,
n = &(*n)->rb_left;
else if (start_blk >= (entry->start_blk + entry->count))
n = &(*n)->rb_right;
else {
if (start_blk + count > (entry->start_blk +
entry->count))
entry->count = (start_blk + count -
entry->start_blk);
new_node = *n;
new_entry = rb_entry(new_node, struct ext4_system_zone,
node);
break;
}
else /* Unexpected overlap of system zones. */
return -EFSCORRUPTED;
}
if (!new_entry) {
new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
GFP_KERNEL);
if (!new_entry)
return -ENOMEM;
new_entry->start_blk = start_blk;
new_entry->count = count;
new_node = &new_entry->node;
new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
GFP_KERNEL);
if (!new_entry)
return -ENOMEM;
new_entry->start_blk = start_blk;
new_entry->count = count;
new_node = &new_entry->node;
rb_link_node(new_node, parent, n);
rb_insert_color(new_node, &sbi->system_blks);
}
rb_link_node(new_node, parent, n);
rb_insert_color(new_node, &sbi->system_blks);
/* Can we merge to the left? */
node = rb_prev(new_node);