ring-buffer: Fix possible dereference of uninitialized pointer

Overview

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

ring-buffer: Fix possible dereference of uninitialized pointer

There is a pointer head_page in rb_meta_validate_events() which is not initialized at the beginning of a function. This pointer can be dereferenced if there is a failure during reader page validation. In this case the control is passed to "invalid" label where the pointer is dereferenced in a loop.

To fix the issue initialize orig_head and head_page before calling rb_validate_buffer.

Found by Linux Verification Center (linuxtesting.org) with SVACE.

Affected

• Linux >= 5f3b6e839f3ceb8d6ef02231ba9b5aca71b8bf55 < a4afdff9c715af50cf6c3f2dc601932c2cea17a2
• Linux >= 5f3b6e839f3ceb8d6ef02231ba9b5aca71b8bf55 < bc77986f3cb7476637052edf2d87137fa39f153d
• Linux >= 5f3b6e839f3ceb8d6ef02231ba9b5aca71b8bf55 < d9942396845fef2369478c157b26738fe07142f6
• Linux >= 5f3b6e839f3ceb8d6ef02231ba9b5aca71b8bf55 < f1547779402c4cd67755c33616b7203baa88420b
• Linux 6.12

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.