CVE-2026-89771
HighCVSS 7.8Exploitation Probability (EPSS)
Low risk2th percentile - higher than 2% of all known CVEs
Summary
In the Linux kernel, a race condition in the ring-buffer during subbuf resize by readers was resolved. trace_buffer subbuf_size is read lockless in ring_buffer_read_page() and ring_buffer_read_start(), while it can simultaneously be resized with ring_buffer_subbuf_order_set(). The fix uses bpage::order instead of trace_buffer::subbuf_size and adds a mutex in ring_buffer_read_start().
Risk Assessment
The race may lead to reading inconsistent data, memory corruption, or kernel crashes during concurrent buffer reads and resizes.
Recommendation
Update the Linux kernel to a version containing the fix that synchronizes buffer reads with subbuf size modifications.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: ring-buffer: Fix subbuf resize race with ring buffer readers trace_buffer subbuf_size is read lockless in ring_buffer_read_page() and ring_buffer_read_start(), while it can simultaneously be resized with ring_buffer_subbuf_order_set(). Instead of trace_buffer::subbuf_size, use bpage::order in ring_buffer_read_start() and ring_buffer_read_page(). In ring_buffer_read_start(), even with resize_disabled, there is still a possibility of a race with a buffer modification. Hold the trace_buffer mutex to synchronise with any pending ring buffer order modification. trace_buffer::subbuf_size is now actually useless, remove it. Also, create accessors rb_subbuf_capacity() and rb_page_capacity() which return the actual size available for storing events, while rb_subbuf_size() returns the actual subbuf page-size.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS