diff options
| author | Andy Lutomirski <luto@amacapital.net> | 2014-06-13 04:53:12 +0400 |
|---|---|---|
| committer | H. Peter Anvin <hpa@zytor.com> | 2014-06-13 06:02:30 +0400 |
| commit | e0bf7b86dace87eccdabdd66d2769ccad19cb81c (patch) | |
| tree | 25ca13ba0e165ab1d16faf266d4b8d8046b7a5f7 /arch/x86/vdso/vdso2c.h | |
| parent | b4b31f6101433e4b8ee73779b69b935af07682f8 (diff) | |
| download | linux-e0bf7b86dace87eccdabdd66d2769ccad19cb81c.tar.xz | |
x86/vdso: Hack to keep 64-bit Go programs working
The Go runtime has a buggy vDSO parser that currently segfaults.
This writes an empty SHT_DYNSYM entry that causes Go's runtime to
malfunction by thinking that the vDSO is empty rather than
malfunctioning by running off the end and segfaulting.
This affects x86-64 only as far as we know, so we do not need this for
the i386 and x32 vdsos.
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Link: http://lkml.kernel.org/r/d10618176c4bd39b457a5e85c497295c90cab1bc.1402620737.git.luto@amacapital.net
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
Diffstat (limited to 'arch/x86/vdso/vdso2c.h')
| -rw-r--r-- | arch/x86/vdso/vdso2c.h | 23 |
1 files changed, 18 insertions, 5 deletions
diff --git a/arch/x86/vdso/vdso2c.h b/arch/x86/vdso/vdso2c.h index d9f6f61aef1c..c6eefaf389b9 100644 --- a/arch/x86/vdso/vdso2c.h +++ b/arch/x86/vdso/vdso2c.h @@ -18,6 +18,8 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name) const char *secstrings; uint64_t syms[NSYMS] = {}; + uint64_t fake_sections_value = 0, fake_sections_size = 0; + Elf_Phdr *pt = (Elf_Phdr *)(addr + GET_LE(&hdr->e_phoff)); /* Walk the segment table. */ @@ -84,6 +86,7 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name) GET_LE(&symtab_hdr->sh_entsize) * i; const char *name = addr + GET_LE(&strtab_hdr->sh_offset) + GET_LE(&sym->st_name); + for (k = 0; k < NSYMS; k++) { if (!strcmp(name, required_syms[k])) { if (syms[k]) { @@ -93,6 +96,13 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name) syms[k] = GET_LE(&sym->st_value); } } + + if (!strcmp(name, "vdso_fake_sections")) { + if (fake_sections_value) + fail("duplicate vdso_fake_sections\n"); + fake_sections_value = GET_LE(&sym->st_value); + fake_sections_size = GET_LE(&sym->st_size); + } } /* Validate mapping addresses. */ @@ -112,11 +122,14 @@ static void GOFUNC(void *addr, size_t len, FILE *outfile, const char *name) if (syms[sym_end_mapping] % 4096) fail("end_mapping must be a multiple of 4096\n"); - /* Remove sections. */ - hdr->e_shoff = 0; - hdr->e_shentsize = 0; - hdr->e_shnum = 0; - hdr->e_shstrndx = SHN_UNDEF; /* SHN_UNDEF == 0 */ + /* Remove sections or use fakes */ + if (fake_sections_size % sizeof(Elf_Shdr)) + fail("vdso_fake_sections size is not a multiple of %ld\n", + (long)sizeof(Elf_Shdr)); + PUT_LE(&hdr->e_shoff, fake_sections_value); + PUT_LE(&hdr->e_shentsize, fake_sections_value ? sizeof(Elf_Shdr) : 0); + PUT_LE(&hdr->e_shnum, fake_sections_size / sizeof(Elf_Shdr)); + PUT_LE(&hdr->e_shstrndx, SHN_UNDEF); if (!name) { fwrite(addr, load_size, 1, outfile); |