USB: gadget: zero allocate endpoint 0 buffers

USB: gadget: zero allocate endpoint 0 buffers

Origin: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/commit?id=6eea4ace62fa6414432692ee44f0c0a3d541d97a
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2021-39685

commit 86ebbc11bb3f60908a51f3e41a17e3f477c2eaa3 upstream.

Under some conditions, USB gadget devices can show allocated buffer
contents to a host.  Fix this up by zero-allocating them so that any
extra data will all just be zeros.

Reported-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Tested-by: Szymon Heidrich <szymon.heidrich@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Gbp-Pq: Topic bugfix/all
Gbp-Pq: Name USB-gadget-zero-allocate-endpoint-0-buffers.patch