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Commit f175d637 authored by Jan Kara's avatar Jan Kara Committed by Greg Kroah-Hartman
Browse files

ext4: don't allow overlapping system zones 



commit bf9a379d0980e7413d94cb18dac73db2bfc5f470 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: 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.cz


Signed-off-by: default avatarTheodore Ts'o <tytso@mit.edu>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent d01b5fc0

fs/ext4/block_validity.c

+12 −22
Original line number Diff line number Diff line
@@ -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;
@@ -68,19 +68,10 @@ 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)
@@ -91,7 +82,6 @@ static int add_system_zone(struct ext4_sb_info *sbi, 


	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);