CVE-2026-89962
UnknownSummary
In the Linux kernel, the __merge_memory_ranges() function (powerpc/kexec_file) has a logic flaw when merging overlapping memory ranges. It compares the current range's start against the previous element instead of the running target index and unconditionally overwrites the range end, causing valid memory ranges to be truncated. As a result, memory fragments may be lost from kexec exclude lists, potentially allowing the crash kernel to overwrite active memory.
Risk Assessment
This flaw can cause data corruption or crashes because the crash kernel may overwrite active memory that should have been excluded. It affects PowerPC systems using kexec.
Recommendation
Update the Linux kernel to a version containing the fix that compares the current range's start against the end of the active merged range and uses max() to safely prevent outer boundary truncation. If updating is not possible, consider restricting kexec usage on affected systems.
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Original NVD description (English source)
In the Linux kernel, the following vulnerability has been resolved: powerpc/kexec_file: Prevent kexec range truncation Sashiko AI review pointed out the following issue. The __merge_memory_ranges() function incorrectly handles overlapping memory ranges when merging them. Although sort_memory_ranges() 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.
Vulnerability data from NVD (NIST) · CISA KEV · EPSS