From: Josef Bacik Date: Fri, 12 Mar 2021 20:25:15 +0000 (-0500) Subject: btrfs: validate root::reloc_root after recording root in trans X-Git-Url: http://git.osdn.net/view?a=commitdiff_plain;h=39200e59089e260af8edb9feeb69c54ba51699c5;p=uclinux-h8%2Flinux.git btrfs: validate root::reloc_root after recording root in trans If we fail to setup a root->reloc_root in a different thread that path will error out, however it still leaves root->reloc_root NULL but would still appear set up in the transaction. Subsequent calls to btrfs_record_root_in_transaction would succeed without attempting to create the reloc root, as the transid has already been updated. Handle this case by making sure we have a root->reloc_root set after a btrfs_record_root_in_transaction call so we don't end up dereferencing a NULL pointer. Reported-by: Zygo Blaxell Signed-off-by: Josef Bacik Reviewed-by: David Sterba Signed-off-by: David Sterba --- diff --git a/fs/btrfs/relocation.c b/fs/btrfs/relocation.c index 11cda7dd7ee6..2d9c0cda5e1c 100644 --- a/fs/btrfs/relocation.c +++ b/fs/btrfs/relocation.c @@ -2082,6 +2082,13 @@ struct btrfs_root *select_reloc_root(struct btrfs_trans_handle *trans, return ERR_PTR(ret); root = root->reloc_root; + /* + * We could have raced with another thread which failed, so + * root->reloc_root may not be set, return ENOENT in this case. + */ + if (!root) + return ERR_PTR(-ENOENT); + if (next->new_bytenr != root->node->start) { /* * We just created the reloc root, so we shouldn't have @@ -2579,6 +2586,14 @@ static int relocate_tree_block(struct btrfs_trans_handle *trans, ret = btrfs_record_root_in_trans(trans, root); if (ret) goto out; + /* + * Another thread could have failed, need to check if we + * have reloc_root actually set. + */ + if (!root->reloc_root) { + ret = -ENOENT; + goto out; + } root = root->reloc_root; node->new_bytenr = root->node->start; btrfs_put_root(node->root);