Report a missing __LINKEDIT segment instead of panicking - #835
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arpitjain099 wants to merge 1 commit into
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Report a missing __LINKEDIT segment instead of panicking#835arpitjain099 wants to merge 1 commit into
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Segment() returns nil for a name it does not find, and the three places that look up __LINKEDIT (and __TEXT) during signing dereference the result straight away. A Mach-O without those segments is malformed, but quill can be handed one, and it panicked on a nil pointer rather than saying what was wrong with the input. Covers the same lookup in AddEmptyCodeSigningCmd, newCodeDirectoryFromMacho and the superblob patch step. The test drives AddEmptyCodeSigningCmd with a Mach-O that has no segments at all; it panics without the guards. Signed-off-by: Arpit Jain <arpitjain099@gmail.com>
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(*macho.File).Segmentreturns nil when it does not find the name, and the three places that look up__LINKEDIT(plus the__TEXTlookup next to one of them) use the result immediately:quill/macho/file.go,AddEmptyCodeSigningCmd:linkEditSeg.Offset + linkEditSeg.Fileszquill/sign/code_directory.go,newCodeDirectoryFromMacho:textSeg.Offset, andlinkEditSeg.Offset + linkEditSeg.Fileszon the no-existing-signature pathquill/sign/signing_super_blob.go:linkEditSegment.Filesz += numSbBytesA Mach-O without those segments is malformed, but quill can be handed one, and today it panics on a nil pointer instead of saying what is wrong with the input. Running
AddEmptyCodeSigningCmdagainst a file with no segments:Each site now returns an error naming the missing segment. Nothing else changes: on a well formed binary all four lookups succeed exactly as before.
The test builds a
Filewith an emptymacho.FilesoSegment("__LINKEDIT")is nil, and drivesAddEmptyCodeSigningCmd. It panics on main and passes here.go build ./...andgo vet ./quill/...are clean, andgo test ./quill/macho/passes.