CVE-2026-64134

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

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

At transition to the ioviter for PCM data transfer, we blindly applied the ioviter 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 interleavedcopy() for addressing the bug above. noninterleavedcopy() has already the NULL data handling, so it doesn't need changes.