From: Qu Wenruo <wqu@xxxxxxxx> [ 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@xxxxxxxxxx> Signed-off-by: Qu Wenruo <wqu@xxxxxxxx> Tested-by: Gu Jinxiang <gujx@xxxxxxxxxxxxxx> Reviewed-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: David Sterba <dsterba@xxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx> --- fs/btrfs/relocation.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-) diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 879b76fa881a..be94c65bb4d2 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -1321,18 +1321,19 @@ static void __del_reloc_root(struct btrfs_root *root) 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); -- 2.17.1
