b7f54894aa
commit c72ea20503610a4a7ba26c769357d31602769c01 upstream.
If we fail to copy the just created file descriptor to userland, we
try to clean up by putting back 'fd' and freeing 'ib'. The code uses
put_unused_fd() for the former which is wrong, as the file descriptor
was already published by fd_install() which gets called internally by
anon_inode_getfd().
This makes the error handling code leaving a half cleaned up file
descriptor table around and a partially destructed 'file' object,
allowing userland to play use-after-free tricks on us, by abusing
the still usable fd and making the code operate on a dangling
'file->private_data' pointer.
Instead of leaving the kernel in a partially corrupted state, don't
attempt to explicitly clean up and leave this to the process exit
path that'll release any still valid fds, including the one created
by the previous call to anon_inode_getfd(). Simply return -EFAULT to
indicate the error.
Fixes: f73f7f4da581 ("iio: buffer: add ioctl() to support opening extra buffers for IIO device")
Cc: stable@kernel.org
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Alexandru Ardelean <ardeleanalex@gmail.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Nuno Sa <Nuno.Sa@analog.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Mathias Krause <minipli@grsecurity.net>
Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.