From: Dan Rosenberg Date: Mon, 19 Jul 2010 20:58:20 +0000 (-0400) Subject: Btrfs: fix checks in BTRFS_IOC_CLONE_RANGE X-Git-Tag: v2.6.33.7~98 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=31f2ec9a89ba61ae1c3cfcd987567f14462a9cb2;p=thirdparty%2Fkernel%2Fstable.git Btrfs: fix checks in BTRFS_IOC_CLONE_RANGE commit 2ebc3464781ad24474abcbd2274e6254689853b5 upstream. 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 Signed-off-by: Chris Mason Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/btrfs/ioctl.c b/fs/btrfs/ioctl.c index 2c6ee6aacb265..0bc5776950612 100644 --- a/fs/btrfs/ioctl.c +++ b/fs/btrfs/ioctl.c @@ -952,7 +952,7 @@ 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); @@ -1005,7 +1005,7 @@ 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;