From 8f5f6178f366bdb93d6af6f2bdca8ebca1ad9fe9 Mon Sep 17 00:00:00 2001 From: Gerhard Heift Date: Thu, 30 Jan 2014 16:23:59 +0100 Subject: [PATCH] btrfs: tree_search, copy_to_sk: return EOVERFLOW for too small buffer In copy_to_sk, if an item is too large for the given buffer, it now returns -EOVERFLOW instead of copying a search_header with len = 0. For backward compatibility for the first item it still copies such a header to the buffer, but not any other following items, which could have fitted. tree_search changes -EOVERFLOW back to 0 to behave similiar to the way it behaved before this patch. Signed-off-by: Gerhard Heift Signed-off-by: Chris Mason Acked-by: David Sterba --- fs/btrfs/ioctl.c | 28 ++++++++++++++++++++++++++-- 1 file changed, 26 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 775640475e35..6e09fc1c1c18 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1990,8 +1990,20 @@ static noinline int copy_to_sk(struct btrfs_root *root, if (!key_in_sk(key, sk)) continue; - if (sizeof(sh) + item_len > buf_size) + if (sizeof(sh) + item_len > buf_size) { + if (*num_found) { + ret = 1; + goto out; + } + + /* + * return one empty item back for v1, which does not + * handle -EOVERFLOW + */ + item_len = 0; + ret = -EOVERFLOW; + } if (sizeof(sh) + item_len + *sk_offset > buf_size) { ret = 1; @@ -2017,6 +2029,9 @@ static noinline int copy_to_sk(struct btrfs_root *root, } (*num_found)++; + if (ret) /* -EOVERFLOW from above */ + goto out; + if (*num_found >= sk->nr_items) { ret = 1; goto out; @@ -2095,7 +2110,8 @@ static noinline int search_ioctl(struct inode *inode, break; } - ret = 0; + if (ret > 0) + ret = 0; err: sk->nr_items = num_found; btrfs_free_path(path); @@ -2118,6 +2134,14 @@ static noinline int btrfs_ioctl_tree_search(struct file *file, inode = file_inode(file); ret = search_ioctl(inode, &args->key, sizeof(args->buf), args->buf); + + /* + * In the origin implementation an overflow is handled by returning a + * search header with a len of zero, so reset ret. + */ + if (ret == -EOVERFLOW) + ret = 0; + if (ret == 0 && copy_to_user(argp, args, sizeof(*args))) ret = -EFAULT; kfree(args); -- 2.11.0