mmap() and mremap() security fixes#2143
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francescolavra merged 2 commits intomasterfrom Mar 7, 2026
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niklasfemerstrand
approved these changes
Mar 3, 2026
added 2 commits
March 7, 2026 08:02
The target address range in a mremap syscall with the MREMAP_FIXED flag must fall within the range assigned to the user process, otherwise the syscall must be rejected with -EINVAL;
When exec protection is enabled, a mapping for an executable file must never be granted write access, even if it's a private mapping, otherwise a program can bypass exec protection by executing arbitrary code in memory.
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The first commit adds a missing validation of the user-supplied address in the mremap() syscall.
The second commit enforces read-only access on executable mappings when exec protection is enabled.
Thanks to Niklas Femerstrand (@niklasfemerstrand) for reporting these issues.