diff --git a/src/cmd/internal/buildid/note.go b/src/cmd/internal/buildid/note.go index f5b6fc565f36dc..ab98701fb569f2 100644 --- a/src/cmd/internal/buildid/note.go +++ b/src/cmd/internal/buildid/note.go @@ -78,16 +78,19 @@ var elfGNUNote = []byte("GNU\x00") // at least 4 kB out, in data. func readELF(name string, f *os.File, data []byte) (buildid string, err error) { // Assume the note content is in the data, already read. - // Rewrite the ELF header to set shnum to 0, so that we can pass + // Rewrite the ELF header to set shoff and shnum to 0, so that we can pass // the data to elf.NewFile and it will decode the Prog list but not // try to read the section headers and the string table from disk. // That's a waste of I/O when all we care about is the Prog list // and the one ELF note. switch elf.Class(data[elf.EI_CLASS]) { case elf.ELFCLASS32: + data[32], data[33], data[34], data[35] = 0, 0, 0, 0 data[48] = 0 data[49] = 0 case elf.ELFCLASS64: + data[40], data[41], data[42], data[43] = 0, 0, 0, 0 + data[44], data[45], data[46], data[47] = 0, 0, 0, 0 data[60] = 0 data[61] = 0 } diff --git a/src/debug/elf/file.go b/src/debug/elf/file.go index aff2b00aae3bcf..db07a2daff8800 100644 --- a/src/debug/elf/file.go +++ b/src/debug/elf/file.go @@ -388,6 +388,52 @@ func NewFile(r io.ReaderAt) (*File, error) { f.Progs[i] = p } + // If the number of sections is greater than or equal to SHN_LORESERVE + // (0xff00), shnum has the value zero and the actual number of section + // header table entries is contained in the sh_size field of the section + // header at index 0. + if shoff > 0 && shnum == 0 { + var typ, link uint32 + sr.Seek(shoff, seekStart) + switch f.Class { + case ELFCLASS32: + sh := new(Section32) + if err := binary.Read(sr, f.ByteOrder, sh); err != nil { + return nil, err + } + shnum = int(sh.Size) + typ = sh.Type + link = sh.Link + case ELFCLASS64: + sh := new(Section64) + if err := binary.Read(sr, f.ByteOrder, sh); err != nil { + return nil, err + } + shnum = int(sh.Size) + typ = sh.Type + link = sh.Link + } + if SectionType(typ) != SHT_NULL { + return nil, &FormatError{shoff, "invalid type of the initial section", SectionType(typ)} + } + + if shnum < int(SHN_LORESERVE) { + return nil, &FormatError{shoff, "invalid ELF shnum contained in sh_size", shnum} + } + + // If the section name string table section index is greater than or + // equal to SHN_LORESERVE (0xff00), this member has the value + // SHN_XINDEX (0xffff) and the actual index of the section name + // string table section is contained in the sh_link field of the + // section header at index 0. + if shstrndx == int(SHN_XINDEX) { + shstrndx = int(link) + if shstrndx < int(SHN_LORESERVE) { + return nil, &FormatError{shoff, "invalid ELF shstrndx contained in sh_link", shstrndx} + } + } + } + // Read section headers f.Sections = make([]*Section, shnum) names := make([]uint32, shnum) diff --git a/src/debug/elf/file_test.go b/src/debug/elf/file_test.go index c0decdd66e482d..fe72a1908f36c1 100644 --- a/src/debug/elf/file_test.go +++ b/src/debug/elf/file_test.go @@ -9,6 +9,7 @@ import ( "compress/gzip" "debug/dwarf" "encoding/binary" + "fmt" "io" "math/rand" "net" @@ -230,7 +231,7 @@ func TestOpen(t *testing.T) { continue } defer f.Close() - if !reflect.DeepEqual(f.FileHeader, tt.hdr) { + if f.FileHeader != tt.hdr { t.Errorf("open %s:\n\thave %#v\n\twant %#v\n", tt.file, f.FileHeader, tt.hdr) continue } @@ -238,18 +239,18 @@ func TestOpen(t *testing.T) { if i >= len(tt.sections) { break } - sh := &tt.sections[i] - if !reflect.DeepEqual(&s.SectionHeader, sh) { - t.Errorf("open %s, section %d:\n\thave %#v\n\twant %#v\n", tt.file, i, &s.SectionHeader, sh) + sh := tt.sections[i] + if s.SectionHeader != sh { + t.Errorf("open %s, section %d:\n\thave %#v\n\twant %#v\n", tt.file, i, s.SectionHeader, sh) } } for i, p := range f.Progs { if i >= len(tt.progs) { break } - ph := &tt.progs[i] - if !reflect.DeepEqual(&p.ProgHeader, ph) { - t.Errorf("open %s, program %d:\n\thave %#v\n\twant %#v\n", tt.file, i, &p.ProgHeader, ph) + ph := tt.progs[i] + if p.ProgHeader != ph { + t.Errorf("open %s, program %d:\n\thave %#v\n\twant %#v\n", tt.file, i, p.ProgHeader, ph) } } tn := len(tt.sections) @@ -944,6 +945,251 @@ func TestNoSectionOverlaps(t *testing.T) { } } +// TestLargeNumberOfSections tests the case that a file has greater than or +// equal to 65280 (0xff00) sections. +func TestLargeNumberOfSections(t *testing.T) { + // A file with >= 0xff00 sections is too big, so we will construct it on the + // fly. The original file "y.o" is generated by these commands: + // 1. generate "y.c": + // for i in `seq 1 65288`; do + // printf -v x "%04x" i; + // echo "int var_$x __attribute__((section(\"section_$x\"))) = $i;" + // done > y.c + // 2. compile: gcc -c y.c -m32 + // + // $readelf -h y.o + // ELF Header: + // Magic: 7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00 + // Class: ELF32 + // Data: 2's complement, little endian + // Version: 1 (current) + // OS/ABI: UNIX - System V + // ABI Version: 0 + // Type: REL (Relocatable file) + // Machine: Intel 80386 + // Version: 0x1 + // Entry point address: 0x0 + // Start of program headers: 0 (bytes into file) + // Start of section headers: 3003468 (bytes into file) + // Flags: 0x0 + // Size of this header: 52 (bytes) + // Size of program headers: 0 (bytes) + // Number of program headers: 0 + // Size of section headers: 40 (bytes) + // Number of section headers: 0 (65298) + // Section header string table index: 65535 (65297) + // + // $readelf -S y.o + // There are 65298 section headers, starting at offset 0x2dd44c: + // Section Headers: + // [Nr] Name Type Addr Off Size ES Flg Lk Inf Al + // [ 0] NULL 00000000 000000 00ff12 00 65297 0 0 + // [ 1] .text PROGBITS 00000000 000034 000000 00 AX 0 0 1 + // [ 2] .data PROGBITS 00000000 000034 000000 00 WA 0 0 1 + // [ 3] .bss NOBITS 00000000 000034 000000 00 WA 0 0 1 + // [ 4] section_0001 PROGBITS 00000000 000034 000004 00 WA 0 0 4 + // [ 5] section_0002 PROGBITS 00000000 000038 000004 00 WA 0 0 4 + // [ section_0003 ~ section_ff06 truncated ] + // [65290] section_ff07 PROGBITS 00000000 03fc4c 000004 00 WA 0 0 4 + // [65291] section_ff08 PROGBITS 00000000 03fc50 000004 00 WA 0 0 4 + // [65292] .comment PROGBITS 00000000 03fc54 000027 01 MS 0 0 1 + // [65293] .note.GNU-stack PROGBITS 00000000 03fc7b 000000 00 0 0 1 + // [65294] .symtab SYMTAB 00000000 03fc7c 0ff0a0 10 65296 2 4 + // [65295] .symtab_shndx SYMTAB SECTION 00000000 13ed1c 03fc28 04 65294 0 4 + // [65296] .strtab STRTAB 00000000 17e944 08f74d 00 0 0 1 + // [65297] .shstrtab STRTAB 00000000 20e091 0cf3bb 00 0 0 1 + + var buf bytes.Buffer + + { + buf.Grow(0x55AF1C) // 3003468 + 40 * 65298 + + h := Header32{ + Ident: [16]byte{0x7F, 'E', 'L', 'F', 0x01, 0x01, 0x01}, + Type: 1, + Machine: 3, + Version: 1, + Shoff: 0x2DD44C, + Ehsize: 0x34, + Shentsize: 0x28, + Shnum: 0, + Shstrndx: 0xFFFF, + } + binary.Write(&buf, binary.LittleEndian, h) + + // Zero out sections [1]~[65294]. + buf.Write(bytes.Repeat([]byte{0}, 0x13ED1C-binary.Size(h))) + + // Write section [65295]. Section [65295] are all zeros except for the + // last 48 bytes. + buf.Write(bytes.Repeat([]byte{0}, 0x03FC28-12*4)) + for i := 0; i < 12; i++ { + binary.Write(&buf, binary.LittleEndian, uint32(0xFF00|i)) + } + + // Write section [65296]. + buf.Write([]byte{0}) + buf.Write([]byte("y.c\x00")) + for i := 1; i <= 65288; i++ { + // var_0001 ~ var_ff08 + name := fmt.Sprintf("var_%04x", i) + buf.Write([]byte(name)) + buf.Write([]byte{0}) + } + + // Write section [65297]. + buf.Write([]byte{0}) + buf.Write([]byte(".symtab\x00")) + buf.Write([]byte(".strtab\x00")) + buf.Write([]byte(".shstrtab\x00")) + buf.Write([]byte(".text\x00")) + buf.Write([]byte(".data\x00")) + buf.Write([]byte(".bss\x00")) + for i := 1; i <= 65288; i++ { + // s_0001 ~ s_ff08 + name := fmt.Sprintf("section_%04x", i) + buf.Write([]byte(name)) + buf.Write([]byte{0}) + } + buf.Write([]byte(".comment\x00")) + buf.Write([]byte(".note.GNU-stack\x00")) + buf.Write([]byte(".symtab_shndx\x00")) + + // Write section header table. + // NULL + binary.Write(&buf, binary.LittleEndian, Section32{Name: 0, Size: 0xFF12, Link: 0xFF11}) + // .text + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x1B, + Type: uint32(SHT_PROGBITS), + Flags: uint32(uint32(SHF_ALLOC | SHF_EXECINSTR)), + Off: 0x34, + Addralign: 0x01, + }) + // .data + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x21, + Type: uint32(SHT_PROGBITS), + Flags: uint32(SHF_WRITE | SHF_ALLOC), + Off: 0x34, + Addralign: 0x01, + }) + // .bss + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x27, + Type: uint32(SHT_NOBITS), + Flags: uint32(SHF_WRITE | SHF_ALLOC), + Off: 0x34, + Addralign: 0x01, + }) + // s_1 ~ s_65537 + for i := 0; i < 65288; i++ { + s := Section32{ + Name: uint32(0x2C + i*13), + Type: uint32(SHT_PROGBITS), + Flags: uint32(SHF_WRITE | SHF_ALLOC), + Off: uint32(0x34 + i*4), + Size: 0x04, + Addralign: 0x04, + } + binary.Write(&buf, binary.LittleEndian, s) + } + // .comment + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x0CF394, + Type: uint32(SHT_PROGBITS), + Flags: uint32(SHF_MERGE | SHF_STRINGS), + Off: 0x03FC54, + Size: 0x27, + Addralign: 0x01, + Entsize: 0x01, + }) + // .note.GNU-stack + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x0CF39D, + Type: uint32(SHT_PROGBITS), + Off: 0x03FC7B, + Addralign: 0x01, + }) + // .symtab + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x01, + Type: uint32(SHT_SYMTAB), + Off: 0x03FC7C, + Size: 0x0FF0A0, + Link: 0xFF10, + Info: 0x02, + Addralign: 0x04, + Entsize: 0x10, + }) + // .symtab_shndx + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x0CF3AD, + Type: uint32(SHT_SYMTAB_SHNDX), + Off: 0x13ED1C, + Size: 0x03FC28, + Link: 0xFF0E, + Addralign: 0x04, + Entsize: 0x04, + }) + // .strtab + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x09, + Type: uint32(SHT_STRTAB), + Off: 0x17E944, + Size: 0x08F74D, + Addralign: 0x01, + }) + // .shstrtab + binary.Write(&buf, binary.LittleEndian, Section32{ + Name: 0x11, + Type: uint32(SHT_STRTAB), + Off: 0x20E091, + Size: 0x0CF3BB, + Addralign: 0x01, + }) + } + + data := buf.Bytes() + + f, err := NewFile(bytes.NewReader(data)) + if err != nil { + t.Errorf("cannot create file from data: %v", err) + } + defer f.Close() + + wantFileHeader := FileHeader{ + Class: ELFCLASS32, + Data: ELFDATA2LSB, + Version: EV_CURRENT, + OSABI: ELFOSABI_NONE, + ByteOrder: binary.LittleEndian, + Type: ET_REL, + Machine: EM_386, + } + if f.FileHeader != wantFileHeader { + t.Errorf("\nhave %#v\nwant %#v\n", f.FileHeader, wantFileHeader) + } + + wantSectionNum := 65298 + if len(f.Sections) != wantSectionNum { + t.Errorf("len(Sections) = %d, want %d", len(f.Sections), wantSectionNum) + } + + wantSectionHeader := SectionHeader{ + Name: "section_0007", + Type: SHT_PROGBITS, + Flags: SHF_WRITE + SHF_ALLOC, + Offset: 0x4c, + Size: 0x4, + Addralign: 0x4, + FileSize: 0x4, + } + if f.Sections[10].SectionHeader != wantSectionHeader { + t.Errorf("\nhave %#v\nwant %#v\n", f.Sections[10].SectionHeader, wantSectionHeader) + } +} + func TestIssue10996(t *testing.T) { data := []byte("\u007fELF\x02\x01\x010000000000000" + "\x010000000000000000000" +