Bug 2502563 (CVE-2026-64134)

Summary: CVE-2026-64134 kernel: ALSA: pcm: Don't setup bogus iov_iter for silencing
Product: [Other] Security Response Reporter: OSIDB Bzimport <bzimport>
Component: vulnerabilityAssignee: Product Security <prodsec-ir-bot>
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Severity: medium Docs Contact:
Priority: medium    
Version: unspecifiedCC: rhel-process-autobot, watson-tool-maintainers
Target Milestone: ---Keywords: Security
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Hardware: All   
OS: Linux   
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A flaw was found in the Linux kernel's Advanced Linux Sound Architecture (ALSA) Pulse Code Modulation (PCM) subsystem. During PCM data transfer, an incorrect setup of the `iov_iter` for silencing (when data is null) could lead to a NULL pointer dereference. This vulnerability can be triggered by a local user, potentially causing a system crash (Denial of Service).
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Description OSIDB Bzimport 2026-07-19 17:06:17 UTC 
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.
Comment 1 TEJ RATHI 2026-07-20 11:02:22 UTC 
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071927-CVE-2026-64134-9e81@gregkh/T