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symbols_map: allow unexpected EOF in ELF files

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Some of the prebuilt ELF files used for bionic heads cause an
unexpected EOF error, ignore unexpected EOF the same way we do
for EOF.

Test: not yet
Change-Id: I267d11b4d12b83ecebedc72a565e148c5e53af6d
This commit is contained in:
Colin Cross 2022-04-11 18:42:34 -07:00
parent 03f951d026
commit 338df53621
2 changed files with 42 additions and 3 deletions
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6
cmd/symbols_map/elf.go
View file

@ -38,13 +38,13 @@ func elfIdentifier(filename string, allowMissing bool) (string, error) {
return elfIdentifierFromReaderAt(f, filename, allowMissing)
}
// elfIdentifier extracts the elf build ID from a ReaderAt. If allowMissing is true it returns
// an empty identifier if the file exists but the build ID note does not.
// elfIdentifierFromReaderAt extracts the elf build ID from a ReaderAt. If allowMissing is true it
// returns an empty identifier if the file exists but the build ID note does not.
func elfIdentifierFromReaderAt(r io.ReaderAt, filename string, allowMissing bool) (string, error) {
f, err := elf.NewFile(r)
if err != nil {
if allowMissing {
if errors.Is(err, io.EOF) {
if errors.Is(err, io.EOF) || errors.Is(err, io.ErrUnexpectedEOF) {
return "", nil
}
if _, ok := err.(*elf.FormatError); ok {

39
cmd/symbols_map/elf_test.go
View file

@ -39,6 +39,10 @@ func Test_elfIdentifierFromReaderAt_BadElfFile(t *testing.T) {
name: "empty elf",
contents: emptyElfFile(),
},
{
name: "short section header",
contents: shortSectionHeaderElfFile(),
},
}
for _, tt := range tests {
@ -111,3 +115,38 @@ func emptyElfFile() string {
binary.Write(buf, binary.LittleEndian, header)
return buf.String()
}
// shortSectionHeader returns an elf file header with a section header that extends past the end of
// the file.
func shortSectionHeaderElfFile() string {
ident := [elf.EI_NIDENT]byte{}
identBuf := bytes.NewBuffer(ident[0:0:elf.EI_NIDENT])
binary.Write(identBuf, binary.LittleEndian, []byte("\x7fELF"))
binary.Write(identBuf, binary.LittleEndian, elf.ELFCLASS64)
binary.Write(identBuf, binary.LittleEndian, elf.ELFDATA2LSB)
binary.Write(identBuf, binary.LittleEndian, elf.EV_CURRENT)
binary.Write(identBuf, binary.LittleEndian, elf.ELFOSABI_LINUX)
binary.Write(identBuf, binary.LittleEndian, make([]byte, 8))
header := elf.Header64{
Ident: ident,
Type: uint16(elf.ET_EXEC),
Machine: uint16(elf.EM_X86_64),
Version: uint32(elf.EV_CURRENT),
Entry: 0,
Phoff: uint64(binary.Size(elf.Header64{})),
Shoff: uint64(binary.Size(elf.Header64{})),
Flags: 0,
Ehsize: uint16(binary.Size(elf.Header64{})),
Phentsize: 0x38,
Phnum: 0,
Shentsize: 0x40,
Shnum: 1,
Shstrndx: 0,
}
buf := &bytes.Buffer{}
binary.Write(buf, binary.LittleEndian, header)
binary.Write(buf, binary.LittleEndian, []byte{0})
return buf.String()
}