[PATCH v3] Btrfs: fix error check of btrfs_lookup_dentry()

[Tsutomu Itoh]

The return value of btrfs_lookup_dentry is checked so that
the panic such as illegal address reference should not occur.

Signed-off-by: Tsutomu Itoh <t-i...@jp.fujitsu.com>
---
V1->V2: unnecessary BUG_ON was deleted
V2->V3: to return -ENOENT instead of NULL when no entry was found,
        return value of btrfs_lookup_dentry is changed.

 fs/btrfs/inode.c |   10 +++++++---
 fs/btrfs/ioctl.c |   10 ++++++++--
 2 files changed, 15 insertions(+), 5 deletions(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 447612d..9210c60 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4025,7 +4025,7 @@ struct inode *btrfs_lookup_dentry(struct inode *dir, 
struct dentry *dentry)
                return ERR_PTR(ret);
 
        if (location.objectid == 0)
-               return NULL;
+               return ERR_PTR(-ENOENT);
 
        if (location.type == BTRFS_INODE_ITEM_KEY) {
                inode = btrfs_iget(dir->i_sb, &location, root, NULL);
@@ -4080,8 +4080,12 @@ static struct dentry *btrfs_lookup(struct inode *dir, 
struct dentry *dentry,
        struct inode *inode;
 
        inode = btrfs_lookup_dentry(dir, dentry);
-       if (IS_ERR(inode))
-               return ERR_CAST(inode);
+       if (IS_ERR(inode)) {
+               if (PTR_ERR(inode) == -ENOENT)
+                       inode = NULL;
+               else
+                       return ERR_CAST(inode);
+       }
 
        return d_splice_alias(inode, dentry);
 }
diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c
index a3c4751..981084d 100644
--- a/fs/btrfs/ioctl.c
+++ b/fs/btrfs/ioctl.c
@@ -325,6 +325,7 @@ static noinline int create_subvol(struct btrfs_root *root,
        struct btrfs_root *new_root;
        struct dentry *parent = dget_parent(dentry);
        struct inode *dir;
+       struct inode *inode;
        int ret;
        int err;
        u64 objectid;
@@ -437,7 +438,13 @@ static noinline int create_subvol(struct btrfs_root *root,
 
        BUG_ON(ret);
 
-       d_instantiate(dentry, btrfs_lookup_dentry(dir, dentry));
+       inode = btrfs_lookup_dentry(dir, dentry);
+       if (IS_ERR(inode)) {
+               ret = PTR_ERR(inode);
+               goto fail;
+       }
+
+       d_instantiate(dentry, inode);
 fail:
        dput(parent);
        if (async_transid) {
@@ -511,7 +518,6 @@ static int create_snapshot(struct btrfs_root *root, struct 
dentry *dentry,
                ret = PTR_ERR(inode);
                goto fail;
        }
-       BUG_ON(!inode);
        d_instantiate(dentry, inode);
        ret = 0;
 fail:


--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html