Re: [PATCH] tee: add overflow check in tee_ioctl_shm_register()

[Greg KH <gregkh@linuxfoundation.org>]

On Mon, Aug 22, 2022 at 11:26:21AM +0200, Jens Wiklander wrote:
> commit 573ae4f13f630d6660008f1974c0a8a29c30e18a upstream.
> 
> With special lengths supplied by user space, tee_shm_register() has
> an integer overflow when calculating the number of pages covered by a
> supplied user space memory region.
> 
> This may cause pin_user_pages_fast() to do a NULL pointer dereference.
> 
> Fix this by adding an an explicit call to access_ok() in
> tee_ioctl_shm_register() to catch an invalid user space address early.
> 
> Fixes: 033ddf12bcf5 ("tee: add register user memory")
> Cc: stable@vger.kernel.org # 5.4
> Reported-by: Nimish Mishra <neelam.nimish@gmail.com>
> Reported-by: Anirban Chakraborty <ch.anirban00727@gmail.com>
> Reported-by: Debdeep Mukhopadhyay <debdeep.mukhopadhyay@gmail.com>
> Suggested-by: Jerome Forissier <jerome.forissier@linaro.org>
> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
> [JW: backport to stable-5.4 + update commit message]

Will this also work for 4.19?

thanks,

greg k-h