From 2ebc3464781ad24474abcbd2274e6254689853b5 Mon Sep 17 00:00:00 2001 From: Dan Rosenberg Date: Mon, 19 Jul 2010 16:58:20 -0400 Subject: [PATCH] Btrfs: fix checks in BTRFS_IOC_CLONE_RANGE 1. The BTRFS_IOC_CLONE and BTRFS_IOC_CLONE_RANGE ioctls should check whether the donor file is append-only before writing to it. 2. The BTRFS_IOC_CLONE_RANGE ioctl appears to have an integer overflow that allows a user to specify an out-of-bounds range to copy from the source file (if off + len wraps around). I haven't been able to successfully exploit this, but I'd imagine that a clever attacker could use this to read things he shouldn't. Even if it's not exploitable, it couldn't hurt to be safe. Signed-off-by: Dan Rosenberg cc: stable@kernel.org Signed-off-by: Chris Mason --- fs/btrfs/ioctl.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 2a8b3a7568ad..9254b3d58dbe 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -1458,7 +1458,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, */ /* the destination must be opened for writing */ - if (!(file->f_mode & FMODE_WRITE)) + if (!(file->f_mode & FMODE_WRITE) || (file->f_flags & O_APPEND)) return -EINVAL; ret = mnt_want_write(file->f_path.mnt); @@ -1511,7 +1511,7 @@ static noinline long btrfs_ioctl_clone(struct file *file, unsigned long srcfd, /* determine range to clone */ ret = -EINVAL; - if (off >= src->i_size || off + len > src->i_size) + if (off + len > src->i_size || off + len < off) goto out_unlock; if (len == 0) olen = len = src->i_size - off;