CVE-2026-89962: powerpc/kexec_file: Prevent kexec range truncation
In the Linux kernel, the following vulnerability has been resolved:
powerpc/kexecfile: Prevent kexec range truncation
Sashiko AI review pointed out the following issue.
The mergememoryranges() function incorrectly handles overlapping memory ranges when merging them. Although sortmemoryranges() sorts all ranges by their start address in ascending order beforehand, the merge logic remains defective in two ways:
1. It compares the current range's start against the previous element (i-1) instead of the running target index (idx)
2. It unconditionally overwrites 'ranges[idx].end' with 'ranges[i].end'.
This logic flaw leads to critical memory truncation when a larger memory range completely subsumes subsequent smaller ranges.
For example, consider a sorted input array with three ranges: Range A (idx=0): [0x1000 - 0x9000] Range B (i=1): [0x2000 - 0x5000] (completely inside Range A) Range C (i=2): [0x6000 - 0x8000] (completely inside Range A)
1. When i=1 (Range B): ranges[1].start (0x2000) <= ranges[0].end + 1 (0x9001) is TRUE. The code executes: ranges[0].end = ranges[1].end, which erroneously shrinks Range A's end from 0x9000 down to 0x5000.
2. When i=2 (Range C): ranges[2].start (0x6000) <= ranges[1].end + 1 (0x5001) is FALSE. The code falls into the else block, creating a broken new range.
As a result, valid memory fragments [0x5001 - 0x5fff] and [0x8001 - 0x9000] are completely lost from the kexec exclude lists, potentially allowing the crash kernel to overwrite active memory, causing data corruption or crashes.
Fix this by ensuring the start of the current range is compared against the end of the active merged range (idx), and use max() to safely prevent the outer boundary from being truncated.
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.111-1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 7.2.6-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.111-1~deb12u1 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.1.191 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.6.160 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.12.110 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 6.18.51 - Upgrade
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linux/Kernelto a version that resolves this vulnerability.Fixed in 7.2.5 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 6.12.115-2Fixed in 7.2.12-1Fixed in 7.2.15-1 - Upgrade
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debian/linux-6.12to a version that resolves this vulnerability.Fixed in 6.12.113-1~deb12u1 - Upgrade
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ubuntu/linux-hwe-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42~24.04.1 - Upgrade
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ubuntu/linux-riscv-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1~24.04.1 - Upgrade
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ubuntu/linuxto a version that resolves this vulnerability.Fixed in 7.0.0-42.42 - Upgrade
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ubuntu/linux-awsto a version that resolves this vulnerability.Fixed in 7.0.0-1016.17 - Upgrade
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ubuntu/linux-gcpto a version that resolves this vulnerability.Fixed in 7.0.0-1016.18 - Upgrade
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ubuntu/linux-ibmto a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oem-7.0to a version that resolves this vulnerability.Fixed in 7.0.0-1017.17 - Upgrade
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ubuntu/linux-oracleto a version that resolves this vulnerability.Fixed in 7.0.0-1015.16 - Upgrade
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ubuntu/linux-riscvto a version that resolves this vulnerability.Fixed in 7.0.0-42.42.1 - Compensating control
Fix the Linux kernel powerpc/kexec_file __merge_memory_ranges() logic by comparing the current range start against the end of the active merged range at index idx, and update the merged end with max(ranges[idx].end, ranges[i].end) so subsumed ranges do not truncate the outer boundary.
Event History
Frequently Asked Questions
Which systems are affected by this issue?
The issue is in the Linux kernel powerpc kexec_file code path. The provided data does not identify affected kernel versions or configurations.
What condition triggers the faulty range merge?
The flaw occurs when sorted memory ranges overlap and a larger range completely contains later, smaller ranges. The merge logic can shrink the larger range by replacing its end address with the end address of a contained range.
What is the practical impact of the defective merge logic?
It can cause critical memory-range truncation during range merging. The description does not state an attacker model, privilege requirement, or a specific resulting security impact beyond the truncation.
How can this be remediated?
Apply a kernel update containing the referenced stable commits. Those commits correct the merge logic so it uses the running merged-range index and does not reduce an existing range end when merging contained ranges.