RemoteInspection: Skip unused ELF section headers #82698
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ELF section headers are allowed to be left uninitialized when the section is empty and unused. LLD is a tad more aggressive about this. The ELF reader in the Swift runtime was a bit aggressive about converting the section headers to names and would not skip over these unused sections headers resulting in crashes due to operating on uninitialized memory in the `sh_name` field. This patch teaches the ELF reader to skip over unused section header table entries.
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@swift-ci please test |
compnerd
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Jul 1, 2025
compnerd
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@swift-ci please test Windows |
al45tair
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Jul 2, 2025
etcwilde
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Jul 10, 2025
ELF section headers are allowed to be left uninitialized when the section is empty and unused. LLD is a tad more aggressive about this. The ELF reader in the Swift runtime was a bit aggressive about converting the section headers to names and would not skip over these unused sections headers resulting in crashes due to operating on uninitialized memory in the `sh_name` field. This patch teaches the ELF reader to skip over unused section header table entries. (cherry picked from commit 14d2088) - Explanation: Fixes a bug where we would read uninitialized data from unused ELF section headers. - Scope: Affects ELF-based platforms and ELF file handling in tools like swift-reflection-dump. - Risk: Low -- Improves implementation according to the spec. Any data used from this was garbage anyway. - Testing: Tested on FreeBSD with LLD, which makes uses of unused section headers. Ensured that runtime and swift-reflection-dump don't crash anymore. - Reviewers: @compnerd, @al45tair Cherry-Pick: swiftlang#82698
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ELF section headers are allowed to be left uninitialized when the section is empty and unused. LLD on FreeBSD is a tad more aggressive about this. The ELF reader in the Swift runtime was a bit aggressive about converting the section headers to names and would not skip over these unused sections headers resulting in crashes due to operating on uninitialized memory in the
sh_namefield.This patch teaches the ELF reader to skip over unused section header table entries.