Commit bf9a379d authored by Jan Kara's avatar Jan Kara Committed by Theodore Ts'o

ext4: don't allow overlapping system zones

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: default avatarLukas Czerner <lczerner@redhat.com>
Signed-off-by: default avatarJan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20200728130437.7804-3-jack@suse.czSigned-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
parent d176b1f6
...@@ -68,7 +68,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, ...@@ -68,7 +68,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks,
ext4_fsblk_t start_blk, ext4_fsblk_t start_blk,
unsigned int count) unsigned int count)
{ {
struct ext4_system_zone *new_entry = NULL, *entry; struct ext4_system_zone *new_entry, *entry;
struct rb_node **n = &system_blks->root.rb_node, *node; struct rb_node **n = &system_blks->root.rb_node, *node;
struct rb_node *parent = NULL, *new_node = NULL; struct rb_node *parent = NULL, *new_node = NULL;
...@@ -79,30 +79,20 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, ...@@ -79,30 +79,20 @@ static int add_system_zone(struct ext4_system_blocks *system_blks,
n = &(*n)->rb_left; n = &(*n)->rb_left;
else if (start_blk >= (entry->start_blk + entry->count)) else if (start_blk >= (entry->start_blk + entry->count))
n = &(*n)->rb_right; n = &(*n)->rb_right;
else { else /* Unexpected overlap of system zones. */
if (start_blk + count > (entry->start_blk + return -EFSCORRUPTED;
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;
}
} }
if (!new_entry) { new_entry = kmem_cache_alloc(ext4_system_zone_cachep,
new_entry = kmem_cache_alloc(ext4_system_zone_cachep, GFP_KERNEL);
GFP_KERNEL); if (!new_entry)
if (!new_entry) return -ENOMEM;
return -ENOMEM; new_entry->start_blk = start_blk;
new_entry->start_blk = start_blk; new_entry->count = count;
new_entry->count = count; new_node = &new_entry->node;
new_node = &new_entry->node;
rb_link_node(new_node, parent, n);
rb_link_node(new_node, parent, n); rb_insert_color(new_node, &system_blks->root);
rb_insert_color(new_node, &system_blks->root);
}
/* Can we merge to the left? */ /* Can we merge to the left? */
node = rb_prev(new_node); node = rb_prev(new_node);
......
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