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Subject[PATCH 4.18 136/197] btrfs: relocation: Only remove reloc rb_trees if reloc control has been initialized
Date
4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Qu Wenruo <wqu@suse.com>

[ Upstream commit 389305b2aa68723c754f88d9dbd268a400e10664 ]

Invalid reloc tree can cause kernel NULL pointer dereference when btrfs
does some cleanup of the reloc roots.

It turns out that fs_info::reloc_ctl can be NULL in
btrfs_recover_relocation() as we allocate relocation control after all
reloc roots have been verified.
So when we hit: note, we haven't called set_reloc_control() thus
fs_info::reloc_ctl is still NULL.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=199833
Reported-by: Xu Wen <wen.xu@gatech.edu>
Signed-off-by: Qu Wenruo <wqu@suse.com>
Tested-by: Gu Jinxiang <gujx@cn.fujitsu.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/btrfs/relocation.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

--- a/fs/btrfs/relocation.c
+++ b/fs/btrfs/relocation.c
@@ -1321,18 +1321,19 @@ static void __del_reloc_root(struct btrf
struct mapping_node *node = NULL;
struct reloc_control *rc = fs_info->reloc_ctl;

- spin_lock(&rc->reloc_root_tree.lock);
- rb_node = tree_search(&rc->reloc_root_tree.rb_root,
- root->node->start);
- if (rb_node) {
- node = rb_entry(rb_node, struct mapping_node, rb_node);
- rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
+ if (rc) {
+ spin_lock(&rc->reloc_root_tree.lock);
+ rb_node = tree_search(&rc->reloc_root_tree.rb_root,
+ root->node->start);
+ if (rb_node) {
+ node = rb_entry(rb_node, struct mapping_node, rb_node);
+ rb_erase(&node->rb_node, &rc->reloc_root_tree.rb_root);
+ }
+ spin_unlock(&rc->reloc_root_tree.lock);
+ if (!node)
+ return;
+ BUG_ON((struct btrfs_root *)node->data != root);
}
- spin_unlock(&rc->reloc_root_tree.lock);
-
- if (!node)
- return;
- BUG_ON((struct btrfs_root *)node->data != root);

spin_lock(&fs_info->trans_lock);
list_del_init(&root->root_list);

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