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Advisory severityHigh7.0Vendor: MediumRed Hat Linux

High [CVE-2026-64402] Fix OOB write in smb_sync_perf_buffer

This high-severity Red Hat Linux advisory covers CVE-2026-64402.

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CVE-2026-64402 Source published Source updated

VulniPulse record published Record updated

CVE-2026-64402
Affected products & platforms
Red Hat LinuxUnclassified
Open source advisory

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Summary

In the Linux kernel, the following vulnerability has been resolved: coresight: ultrasoc-smb: Fix OOB write in smb_sync_perf_buffer() When the SMB sink is used as a perf AUX sink, smb_update_buffer() calls smb_sync_perf_buffer() to copy hardware trace data into the perf AUX ring buffer pages.

It derives pg_idx = head >> PAGE_SHIFT from @head, which is handle->head, and indexes dst_pages[pg_idx]. The pg_idx %= nr_pages normalization is only applied after the first loop iteration.

This leaves the initial page index underived from the buffer size, which can result in an out-of-bounds write past dst_pages[] when head exceeds the AUX buffer size. Normalize head modulo the AUX buffer size before deriving the page index and offset, mirroring tmc_etr_sync_perf_buffer().

This vulnerability involves an out-of-bounds write in the `smb_sync_perf_buffer()` function. An attacker could potentially exploit this by causing the system to write data beyond the intended memory buffer, which may lead to system instability or a denial of service (DoS).

This occurs because a page index is calculated incorrectly before being properly normalized, allowing the system to access memory outside its allocated boundaries. Red Hat severity: Moderate — CVSS 7 (CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H).

Weakness: CWE-787.

Affected versions

No affected-version range was extracted from the source record. The vendor advisory is authoritative. Check it before change work.

Official advisory · medium-confidence parse· fetched 27 days ago·verify at source

Fixed versions

No fixed release is recorded yet. That does not prove no patch exists. Confirm against the vendor advisory.

Official advisory · medium-confidence parse· fetched 27 days ago·verify at source

Mitigation

The source record does not include mitigation steps. That does not mean no fix exists. Read the vendor advisory below for the authoritative guidance.

Official advisory · medium-confidence parse· fetched 27 days ago·verify at source

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