Kernel panic via unsynchronized RISC-V instruction cache
Published May 21, 2024 · Updated May 11, 2026
Kernel panic in the RISC-V code in Linux allows local users to crash affected systems during ftrace instruction patching. patch_text_nosync updates executable instructions and reaches riscv_cpuid_to_hartid_mask through a cross-CPU fence before synchronizing the current CPU instruction cache. The stale cache executes an illegal instruction and panics the kernel; exploitation requires local access, RISC-V hardware, and ftrace patching.
Summary
What happened
Kernel panic in the RISC-V code in Linux allows local users to crash affected systems during ftrace instruction patching. patch_text_nosync updates executable instructions and reaches riscv_cpuid_to_hartid_mask through a cross-CPU fence before synchronizing the current CPU instruction cache. The stale cache executes an illegal instruction and panics the kernel; exploitation requires local access, RISC-V hardware, and ftrace patching.
The record
- CVE
- CVE-2021-47414
- Published
- May 21, 2024
- Updated
- May 11, 2026
- Vendor
- The Linux Kernel Organization
- Product
- Linux
- Classifications
- T1499.004
- Attack vector
- local
- Privileges
- authenticated
Timeline
How it unfolded
- May 21, 2024CVE publishedPublication date reported by the CVE source.
- May 11, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=4.15
- Affected versionversion=fab957c11efe2f405e08b9f0d080524bc2631428 <427faa29e06f0709476ea1bd59758f997ec8b64e
- Affected versionversion=fab957c11efe2f405e08b9f0d080524bc2631428 <bb8958d5dc79acbd071397abb57b8756375fe1ce
- Affected versionversion=fab957c11efe2f405e08b9f0d080524bc2631428 <f1c7aa87c423e765e3862349c2f095fdfccdd9b3
What conditions does exploitation require?
What is affected?
Published CVSS scores
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Attacks
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Weakness, pattern, technique
Public exploit references
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Technologies
Your stack
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Your stack
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