CVE-2026-99158ring-buffer: Fix false warning in ring_buffer_map_get_reader()

Official description

In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Fix false warning in ring_buffer_map_get_reader() The mmap reader can warn when it catches up with a writer that is still committing events. rb_get_reader_page() returns NULL in this case, but ring_buffer_map_get_reader() treats that result as an error. The initial rb_per_cpu_empty() check filters out an empty buffer, but it does not guarantee that the next reader page has committed data. Writers do not take reader_lock and can advance commit_page before publishing the committed length on the new page. rb_get_reader_page() can swap to that page, catch up with the writer and return NULL. Handle NULL through the existing no-data exit without warning. Remove the caller's reader_page == commit_page check as well, since the reader-page helper already handles that case. The existing metadata update and return path remain in place.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/32751946f9b3e502e3d6e42d98b343473112f887
• https://git.kernel.org/stable/c/029770f5badedc0f0ff85fc45e24785cbbee4a67
• https://git.kernel.org/stable/c/68e6ab180cfb6dfa79652f41ed7899a6d4cf5438
• https://git.kernel.org/stable/c/89bab1dba8a0167ef0d819e0f55b6bafa038e87f