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ppc: sanity check writing relocs
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Check for output buffer overruns.

	* elf32-ppc.c (swap_reloc_out, count_and_swap_reloc_out): New
	functions.  Use throughout file.
	* elf64-ppc.c (swap_reloc_out, count_and_swap_reloc_out): Likewise.
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@amodra
amodra committed Aug 4, 2023
1 parent ae33771 commit 066c738
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Showing 2 changed files with 72 additions and 61 deletions.
63 changes: 37 additions & 26 deletions bfd/elf32-ppc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6935,6 +6935,23 @@ is_insn_dq_form (unsigned int insn)
&& (insn & 3) == 1));
}

static bool
swap_reloc_out (bfd *obfd, Elf_Internal_Rela *rel, bfd_byte *loc, asection *s)
{
if ((size_t) (loc - s->contents) >= s->size)
return false;
bfd_elf32_swap_reloca_out (obfd, rel, loc);
return true;
}

static bool
count_and_swap_reloc_out (bfd *obfd, Elf_Internal_Rela *rel, asection *s)
{
bfd_byte *loc = s->contents;
loc += s->reloc_count++ * sizeof (Elf32_External_Rela);
return swap_reloc_out (obfd, rel, loc, s);
}

/* The RELOCATE_SECTION function is called by the ELF backend linker
to handle the relocations for a section.
Expand Down Expand Up @@ -7806,7 +7823,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
: sym->st_shndx != SHN_ABS)))
{
asection *rsec = htab->elf.srelgot;
bfd_byte * loc;

if (ifunc != NULL)
{
Expand All @@ -7825,11 +7841,9 @@ ppc_elf_relocate_section (bfd *output_bfd,
outrel.r_info = ELF32_R_INFO (indx, R_PPC_DTPMOD32);
if (tls_ty == (TLS_TLS | TLS_GD))
{
loc = rsec->contents;
loc += (rsec->reloc_count++
* sizeof (Elf32_External_Rela));
bfd_elf32_swap_reloca_out (output_bfd,
&outrel, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd,
&outrel,
rsec));
outrel.r_offset += 4;
outrel.r_info
= ELF32_R_INFO (indx, R_PPC_DTPREL32);
Expand All @@ -7856,10 +7870,8 @@ ppc_elf_relocate_section (bfd *output_bfd,
outrel.r_addend -= htab->elf.tls_sec->vma;
}
}
loc = rsec->contents;
loc += (rsec->reloc_count++
* sizeof (Elf32_External_Rela));
bfd_elf32_swap_reloca_out (output_bfd, &outrel, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd,
&outrel, rsec));
}

/* Init the .got section contents if we're not
Expand Down Expand Up @@ -8089,7 +8101,6 @@ ppc_elf_relocate_section (bfd *output_bfd,
&& h->dyn_relocs != NULL))
{
int skip;
bfd_byte *loc;
asection *sreloc;
long indx = 0;

Expand Down Expand Up @@ -8221,9 +8232,8 @@ ppc_elf_relocate_section (bfd *output_bfd,
if (sreloc == NULL)
return false;

loc = sreloc->contents;
loc += sreloc->reloc_count++ * sizeof (Elf32_External_Rela);
bfd_elf32_swap_reloca_out (output_bfd, &outrel, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd, &outrel,
sreloc));

if (skip == -1)
goto copy_reloc;
Expand Down Expand Up @@ -9573,7 +9583,8 @@ write_global_sym_plt (struct elf_link_hash_entry *h, void *inf)
rela.r_info = ELF32_R_INFO (htab->elf.hgot->indx,
R_PPC_ADDR16_HA);
rela.r_addend = got_offset;
bfd_elf32_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (info->output_bfd, &rela, loc,
htab->srelplt2));
loc += sizeof (Elf32_External_Rela);

/* Provide the @l relocation for the second instruction. */
Expand All @@ -9583,7 +9594,8 @@ write_global_sym_plt (struct elf_link_hash_entry *h, void *inf)
rela.r_info = ELF32_R_INFO (htab->elf.hgot->indx,
R_PPC_ADDR16_LO);
rela.r_addend = got_offset;
bfd_elf32_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (info->output_bfd, &rela, loc,
htab->srelplt2));
loc += sizeof (Elf32_External_Rela);

/* Provide a relocation for the GOT entry corresponding to this
Expand All @@ -9594,7 +9606,8 @@ write_global_sym_plt (struct elf_link_hash_entry *h, void *inf)
rela.r_info = ELF32_R_INFO (htab->elf.hplt->indx,
R_PPC_ADDR32);
rela.r_addend = ent->plt.offset + 16;
bfd_elf32_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (info->output_bfd, &rela, loc,
htab->srelplt2));
}

/* VxWorks uses non-standard semantics for R_PPC_JMP_SLOT.
Expand Down Expand Up @@ -9676,7 +9689,8 @@ write_global_sym_plt (struct elf_link_hash_entry *h, void *inf)
if (h->type == STT_GNU_IFUNC && is_static_defined (h))
htab->maybe_local_ifunc_resolver = 1;
}
bfd_elf32_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (info->output_bfd, &rela,
loc, relplt));
}
doneone = true;
}
Expand Down Expand Up @@ -9793,9 +9807,8 @@ ppc_finish_symbols (struct bfd_link_info *info)
+ plt->output_offset
+ plt->output_section->vma);
rela.r_addend = val;
loc = relplt->contents + (relplt->reloc_count++
* sizeof (Elf32_External_Rela));
bfd_elf32_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (count_and_swap_reloc_out (info->output_bfd, &rela,
relplt));

p = (unsigned char *) htab->glink->contents + ent->glink_offset;
write_glink_stub (NULL, ent, htab->elf.iplt, p, info);
Expand Down Expand Up @@ -9879,7 +9892,6 @@ ppc_elf_finish_dynamic_symbol (bfd *output_bfd,
{
asection *s;
Elf_Internal_Rela rela;
bfd_byte *loc;

/* This symbols needs a copy reloc. Set it up. */

Expand All @@ -9900,8 +9912,7 @@ ppc_elf_finish_dynamic_symbol (bfd *output_bfd,
rela.r_offset = SYM_VAL (h);
rela.r_info = ELF32_R_INFO (h->dynindx, R_PPC_COPY);
rela.r_addend = 0;
loc = s->contents + s->reloc_count++ * sizeof (Elf32_External_Rela);
bfd_elf32_swap_reloca_out (output_bfd, &rela, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd, &rela, s));
}

#ifdef DEBUG
Expand Down Expand Up @@ -10105,7 +10116,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
+ 2);
rela.r_info = ELF32_R_INFO (htab->elf.hgot->indx, R_PPC_ADDR16_HA);
rela.r_addend = 0;
bfd_elf32_swap_reloca_out (output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (output_bfd, &rela, loc, htab->srelplt2));
loc += sizeof (Elf32_External_Rela);

/* Output the @l relocation for the second instruction. */
Expand All @@ -10114,7 +10125,7 @@ ppc_elf_finish_dynamic_sections (bfd *output_bfd,
+ 6);
rela.r_info = ELF32_R_INFO (htab->elf.hgot->indx, R_PPC_ADDR16_LO);
rela.r_addend = 0;
bfd_elf32_swap_reloca_out (output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (output_bfd, &rela, loc, htab->srelplt2));
loc += sizeof (Elf32_External_Rela);

/* Fix up the remaining relocations. They may have the wrong
Expand Down
70 changes: 35 additions & 35 deletions bfd/elf64-ppc.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -11569,6 +11569,24 @@ get_relocs (asection *sec, int count)
return relocs;
}

static bool
swap_reloc_out (bfd *obfd, Elf_Internal_Rela *rel, bfd_byte *loc, asection *s)
{
if ((size_t) (loc - s->contents) >= s->size)
return false;
bfd_elf64_swap_reloca_out (obfd, rel, loc);
return true;
}

static bool
count_and_swap_reloc_out (bfd *obfd, Elf_Internal_Rela *rel, asection *s)
{
bfd_byte *loc = s->contents;
loc += s->reloc_count++ * sizeof (Elf64_External_Rela);
return swap_reloc_out (obfd, rel, loc, s);
}


/* Convert the relocs R[0] thru R[-NUM_REL+1], which are all no-symbol
forms, to the equivalent relocs against the global symbol given by
STUB_ENTRY->H. */
Expand Down Expand Up @@ -11847,18 +11865,15 @@ ppc_build_one_stub (struct bfd_hash_entry *gen_entry, void *in_arg)
{
/* Create a reloc for the branch lookup table entry. */
Elf_Internal_Rela rela;
bfd_byte *rl;

rela.r_offset = (br_entry->offset
+ htab->brlt->output_offset
+ htab->brlt->output_section->vma);
rela.r_info = ELF64_R_INFO (0, R_PPC64_RELATIVE);
rela.r_addend = targ;

rl = htab->relbrlt->contents;
rl += (htab->relbrlt->reloc_count++
* sizeof (Elf64_External_Rela));
bfd_elf64_swap_reloca_out (htab->relbrlt->owner, &rela, rl);
BFD_ASSERT (count_and_swap_reloc_out (htab->relbrlt->owner, &rela,
htab->relbrlt));
}
else if (info->emitrelocations)
{
Expand Down Expand Up @@ -14652,9 +14667,8 @@ build_global_entry_stubs_and_plt (struct elf_link_hash_entry *h, void *inf)
rela.r_offset = (plt->output_section->vma
+ plt->output_offset
+ ent->plt.offset);
loc = relplt->contents + (relplt->reloc_count++
* sizeof (Elf64_External_Rela));
bfd_elf64_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (count_and_swap_reloc_out (info->output_bfd, &rela,
relplt));
}
}
else
Expand All @@ -14669,7 +14683,8 @@ build_global_entry_stubs_and_plt (struct elf_link_hash_entry *h, void *inf)
/ PLT_ENTRY_SIZE (htab) * sizeof (Elf64_External_Rela)));
if (h->type == STT_GNU_IFUNC && is_static_defined (h))
htab->elf.ifunc_resolvers = true;
bfd_elf64_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (swap_reloc_out (info->output_bfd, &rela,
loc, htab->elf.srelplt));
}
}

Expand Down Expand Up @@ -14790,7 +14805,6 @@ write_plt_relocs_for_local_syms (struct bfd_link_info *info)
Elf_Internal_Sym *sym;
asection *sym_sec;
asection *plt, *relplt;
bfd_byte *loc;
bfd_vma val;

if (!get_sym_h (NULL, &sym, &sym_sec, NULL, &local_syms,
Expand Down Expand Up @@ -14822,7 +14836,7 @@ write_plt_relocs_for_local_syms (struct bfd_link_info *info)

if (relplt == NULL)
{
loc = plt->contents + ent->plt.offset;
bfd_byte *loc = plt->contents + ent->plt.offset;
bfd_put_64 (info->output_bfd, val, loc);
if (htab->opd_abi)
{
Expand Down Expand Up @@ -14851,9 +14865,8 @@ write_plt_relocs_for_local_syms (struct bfd_link_info *info)
rela.r_info = ELF64_R_INFO (0, R_PPC64_RELATIVE);
}
rela.r_addend = val;
loc = relplt->contents + (relplt->reloc_count++
* sizeof (Elf64_External_Rela));
bfd_elf64_swap_reloca_out (info->output_bfd, &rela, loc);
BFD_ASSERT (count_and_swap_reloc_out (info->output_bfd,
&rela, relplt));
}
}

Expand Down Expand Up @@ -16991,11 +17004,9 @@ ppc64_elf_relocate_section (bfd *output_bfd,
outrel.r_info = ELF64_R_INFO (indx, R_PPC64_DTPMOD64);
if (tls_type == (TLS_TLS | TLS_GD))
{
loc = relgot->contents;
loc += (relgot->reloc_count++
* sizeof (Elf64_External_Rela));
bfd_elf64_swap_reloca_out (output_bfd,
&outrel, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd,
&outrel,
relgot));
outrel.r_offset += 8;
outrel.r_addend = orig_rel.r_addend;
outrel.r_info
Expand Down Expand Up @@ -17035,12 +17046,8 @@ ppc64_elf_relocate_section (bfd *output_bfd,
}
if (!(info->enable_dt_relr
&& ELF64_R_TYPE (outrel.r_info) == R_PPC64_RELATIVE))
{
loc = relgot->contents;
loc += (relgot->reloc_count++
* sizeof (Elf64_External_Rela));
bfd_elf64_swap_reloca_out (output_bfd, &outrel, loc);
}
BFD_ASSERT (count_and_swap_reloc_out (output_bfd,
&outrel, relgot));
}

/* Init the .got section contents here if we're not
Expand Down Expand Up @@ -17526,12 +17533,8 @@ ppc64_elf_relocate_section (bfd *output_bfd,
if (sreloc == NULL)
abort ();

if (sreloc->reloc_count * sizeof (Elf64_External_Rela)
>= sreloc->size)
abort ();
loc = sreloc->contents;
loc += sreloc->reloc_count++ * sizeof (Elf64_External_Rela);
bfd_elf64_swap_reloca_out (output_bfd, &outrel, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd, &outrel,
sreloc));
}

if (!warned_dynamic
Expand Down Expand Up @@ -18164,7 +18167,6 @@ ppc64_elf_finish_dynamic_symbol (bfd *output_bfd,
/* This symbol needs a copy reloc. Set it up. */
Elf_Internal_Rela rela;
asection *srel;
bfd_byte *loc;

if (h->dynindx == -1)
abort ();
Expand All @@ -18176,9 +18178,7 @@ ppc64_elf_finish_dynamic_symbol (bfd *output_bfd,
srel = htab->elf.sreldynrelro;
else
srel = htab->elf.srelbss;
loc = srel->contents;
loc += srel->reloc_count++ * sizeof (Elf64_External_Rela);
bfd_elf64_swap_reloca_out (output_bfd, &rela, loc);
BFD_ASSERT (count_and_swap_reloc_out (output_bfd, &rela, srel));
}

return true;
Expand Down

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