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Prevent finalization of pfelf files while using their data. #877

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Prevent finalization of pfelf files while using their data. #877

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6 changes: 5 additions & 1 deletion libpf/pfelf/file.go
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@florianl florianl Oct 27, 2025

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What is the reason to place runtime.KeepAlive in the selected public API functions but leave other functions of *File without it?

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@umanwizard umanwizard Oct 27, 2025

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Those were the only functions I happened to notice where we are getting a pointer to mmap'ed space, then possibly dropping the file (causing an munmap), then trying to access the mmap'ed pointer.

Is there another such function I missed?

Original file line number Diff line number Diff line change
Expand Up @@ -28,6 +28,7 @@ import (
"hash/crc32"
"io"
"path/filepath"
"runtime"
"runtime/debug"
"sort"
"syscall"
Expand Down Expand Up @@ -580,7 +581,7 @@ func (f *File) GetBuildID() (string, error) {
if err != nil {
return "", err
}

runtime.KeepAlive(f)
return getBuildIDFromNotes(data)
}

Expand Down Expand Up @@ -716,6 +717,7 @@ func (f *File) insertTLSDescriptorsForSection(descs map[string]libpf.Address,

descs[symStr] = libpf.Address(rela.Off)
}
runtime.KeepAlive(f)

return nil
}
Expand All @@ -732,6 +734,7 @@ func (f *File) GetDebugLink() (linkName string, crc int32, err error) {
if err != nil {
return "", 0, fmt.Errorf("could not read link: %w", ErrNoDebugLink)
}
runtime.KeepAlive(f)
return ParseDebugLink(d)
}

Expand Down Expand Up @@ -1090,6 +1093,7 @@ func (f *File) visitSymbolTable(name string, visitor func(libpf.Symbol)) error {
})
}
}
runtime.KeepAlive(f)
return nil
}

Expand Down