From 1373f884a081d336aafd9ed742229fb2cd7a3613 Mon Sep 17 00:00:00 2001 From: Jan Kara Date: Tue, 28 Jul 2020 15:04:33 +0200 Subject: [PATCH] ext4: don't allow overlapping system zones [ Upstream commit bf9a379d0980e7413d94cb18dac73db2bfc5f470 ] 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 Signed-off-by: Jan Kara Link: https://lore.kernel.org/r/20200728130437.7804-3-jack@suse.cz Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/block_validity.c | 34 ++++++++++++---------------------- 1 file changed, 12 insertions(+), 22 deletions(-) diff --git a/fs/ext4/block_validity.c b/fs/ext4/block_validity.c index d203cc935ff8..552164034d34 100644 --- a/fs/ext4/block_validity.c +++ b/fs/ext4/block_validity.c @@ -68,7 +68,7 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, 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 = &system_blks->root.rb_node, *node; struct rb_node *parent = NULL, *new_node = NULL; @@ -79,30 +79,20 @@ static int add_system_zone(struct ext4_system_blocks *system_blks, 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, &system_blks->root); - } + rb_link_node(new_node, parent, n); + rb_insert_color(new_node, &system_blks->root); /* Can we merge to the left? */ node = rb_prev(new_node);