From 4891aca2dac612a2f21a3278d9906ade13b55788 Mon Sep 17 00:00:00 2001 From: David Sterba Date: Tue, 19 Apr 2011 16:45:00 +0200 Subject: [PATCH] btrfs: fix dereference before check The superblock's ->s_fs_info is properly set in btrfs_fill_super, after a call to open_ctree, which derefereces it before check. Although tree_root is set via btrfs_set_super, let's be defensive and leave the check in place. Signed-off-by: David Sterba --- fs/btrfs/disk-io.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/disk-io.c b/fs/btrfs/disk-io.c index 990afa8656a2..25e4b8f1d0ef 100644 --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -1611,7 +1611,7 @@ struct btrfs_root *open_ctree(struct super_block *sb, struct btrfs_root *csum_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS); struct btrfs_root *tree_root = btrfs_sb(sb); - struct btrfs_fs_info *fs_info = tree_root->fs_info; + struct btrfs_fs_info *fs_info = NULL; struct btrfs_root *chunk_root = kzalloc(sizeof(struct btrfs_root), GFP_NOFS); struct btrfs_root *dev_root = kzalloc(sizeof(struct btrfs_root), @@ -1623,11 +1623,12 @@ struct btrfs_root *open_ctree(struct super_block *sb, struct btrfs_super_block *disk_super; - if (!extent_root || !tree_root || !fs_info || + if (!extent_root || !tree_root || !tree_root->fs_info || !chunk_root || !dev_root || !csum_root) { err = -ENOMEM; goto fail; } + fs_info = tree_root->fs_info; ret = init_srcu_struct(&fs_info->subvol_srcu); if (ret) { -- 2.39.5