4.9-stable review patch. If anyone has any objections, please let me know.
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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 @@ -1325,18 +1325,19 @@ static void __del_reloc_root(struct btrf struct mapping_node *node = NULL; struct reloc_control *rc = root->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(&root->fs_info->trans_lock); list_del_init(&root->root_list);