In the Linux kernel, the following vulnerability has been resolved: ALSA: pcm: Don't setup bogus iov_iter for silencing At transition to t

In the Linux kernel, the following vulnerability has been resolved:

ALSA: pcm: Don't setup bogus iov_iter for silencing

At transition to the iov_iter for PCM data transfer, we blindly
applied the iov_iter setup also for silencing (i.e. data = NULL), and
it leads to a calculation of bogus iov_iter. Fortunately this didn't
cause troubles on most of architectures but it goes wrong on RISC-V
now, causing a NULL dereference.

Handle the NULL data case to treat the silencing in interleaved_copy()
for addressing the bug above. noninterleaved_copy() has already the
NULL data handling, so it doesn't need changes.