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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 <dan.j.rosenberg@gmail.com>
cc: stable@kernel.org
Signed-off-by: Chris Mason <chris.mason@oracle.com>
This commit is contained in:
Dan Rosenberg 2010-07-19 16:58:20 -04:00 committed by Chris Mason
parent b5384d48f4
commit 2ebc346478
1 changed files with 2 additions and 2 deletions
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4
fs/btrfs/ioctl.c
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@ -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;