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PTR_ADD and NPTR_ADD for bfd.h

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This defines a couple of macros used to avoid ubsan complaints about
calculations involving NULL pointers.  PTR_ADD should be used in the
case where it is known that the offset is always zero with a NULL
pointer, and you'd like to know if a non-zero offset is ever used.
NPTR_ADD should be rarely used, but is defined for cases where a
non-zero offset is expected and should be ignored if the pointer is
NULL.

bfd/
	* bfd-in.h (PTR_ADD, NPTR_ADD): Define.
	* bfd-in2.h: Regenerate.
	* elf-eh-frame.c (adjust_eh_frame_local_symbols): Avoid NULL
	pointer calculations.
	* elflink.c (_bfd_elf_strip_zero_sized_dynamic_sections): Likewise.
	(bfd_elf_add_dt_needed_tag, elf_finalize_dynstr): Likewise.
	(elf_link_add_object_symbols, elf_link_input_bfd): Likewise.
	(bfd_elf_final_link, bfd_elf_gc_record_vtinherit): Likewise.
binutils/
	* objdump.c (disassemble_section): Use PTR_ADD for rel_ppend.
This commit is contained in:
Alan Modra 2021-09-02 09:04:52 +09:30
parent 76aa354424
commit 36f61bf2ad
5 changed files with 39 additions and 26 deletions
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5
bfd/bfd-in.h
View file

@ -113,6 +113,11 @@ typedef struct bfd bfd;
# define TRUE 1
#endif
/* Silence "applying zero offset to null pointer" UBSAN warnings. */
#define PTR_ADD(P,A) ((A) ? (P) + (A) : (P))
/* Also prevent non-zero offsets from being applied to a null pointer. */
#define NPTR_ADD(P,A) ((P) ? (P) + (A) : (P))
#ifdef BFD64
#ifndef BFD_HOST_64_BIT

5
bfd/bfd-in2.h
View file

@ -120,6 +120,11 @@ typedef struct bfd bfd;
# define TRUE 1
#endif
/* Silence "applying zero offset to null pointer" UBSAN warnings. */
#define PTR_ADD(P,A) ((A) ? (P) + (A) : (P))
/* Also prevent non-zero offsets from being applied to a null pointer. */
#define NPTR_ADD(P,A) ((P) ? (P) + (A) : (P))
#ifdef BFD64
#ifndef BFD_HOST_64_BIT

30
bfd/elf-eh-frame.c
View file

@ -1440,25 +1440,27 @@ static int
adjust_eh_frame_local_symbols (const asection *sec,
struct elf_reloc_cookie *cookie)
{
unsigned int shndx;
Elf_Internal_Sym *sym;
Elf_Internal_Sym *end_sym;
int adjusted = 0;
shndx = elf_section_data (sec)->this_idx;
end_sym = cookie->locsyms + cookie->locsymcount;
for (sym = cookie->locsyms + 1; sym < end_sym; ++sym)
if (sym->st_info <= ELF_ST_INFO (STB_LOCAL, STT_OBJECT)
&& sym->st_shndx == shndx)
{
bfd_signed_vma delta = offset_adjust (sym->st_value, sec);
if (cookie->locsymcount > 1)
{
unsigned int shndx = elf_section_data (sec)->this_idx;
Elf_Internal_Sym *end_sym = cookie->locsyms + cookie->locsymcount;
Elf_Internal_Sym *sym;
if (delta != 0)
for (sym = cookie->locsyms + 1; sym < end_sym; ++sym)
if (sym->st_info <= ELF_ST_INFO (STB_LOCAL, STT_OBJECT)
&& sym->st_shndx == shndx)
{
adjusted = 1;
sym->st_value += delta;
bfd_signed_vma delta = offset_adjust (sym->st_value, sec);
if (delta != 0)
{
adjusted = 1;
sym->st_value += delta;
}
}
}
}
return adjusted;
}

23
bfd/elflink.c
View file

@ -3649,7 +3649,7 @@ _bfd_elf_strip_zero_sized_dynamic_sections (struct bfd_link_info *info)
else
pp = &s->next;
if (strip_zero_sized_plt)
if (strip_zero_sized_plt && sdynamic->size != 0)
for (extdyn = sdynamic->contents;
extdyn < sdynamic->contents + sdynamic->size;
extdyn = next)
@ -3709,7 +3709,7 @@ bfd_elf_add_dt_needed_tag (bfd *abfd, struct bfd_link_info *info)
bed = get_elf_backend_data (hash_table->dynobj);
sdyn = bfd_get_linker_section (hash_table->dynobj, ".dynamic");
if (sdyn != NULL)
if (sdyn != NULL && sdyn->size != 0)
for (extdyn = sdyn->contents;
extdyn < sdyn->contents + sdyn->size;
extdyn += bed->s->sizeof_dyn)
@ -3858,7 +3858,7 @@ elf_finalize_dynstr (bfd *output_bfd, struct bfd_link_info *info)
/* Update all .dynamic entries referencing .dynstr strings. */
for (extdyn = sdyn->contents;
extdyn < sdyn->contents + sdyn->size;
extdyn < PTR_ADD (sdyn->contents, sdyn->size);
extdyn += bed->s->sizeof_dyn)
{
Elf_Internal_Dyn dyn;
@ -4276,7 +4276,7 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info)
| DYN_NO_NEEDED)) == 0;
s = bfd_get_section_by_name (abfd, ".dynamic");
if (s != NULL)
if (s != NULL && s->size != 0)
{
bfd_byte *dynbuf;
bfd_byte *extdyn;
@ -4650,7 +4650,7 @@ elf_link_add_object_symbols (bfd *abfd, struct bfd_link_info *info)
(_("%pB: plugin needed to handle lto object"), abfd);
}
for (isym = isymbuf, isymend = isymbuf + extsymcount;
for (isym = isymbuf, isymend = PTR_ADD (isymbuf, extsymcount);
isym < isymend;
isym++, sym_hash++, ever = (ever != NULL ? ever + 1 : NULL))
{
@ -10913,7 +10913,7 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
/* Find local symbol sections and adjust values of symbols in
SEC_MERGE sections. Write out those local symbols we know are
going into the output file. */
isymend = isymbuf + locsymcount;
isymend = PTR_ADD (isymbuf, locsymcount);
for (isym = isymbuf, pindex = flinfo->indices, ppsection = flinfo->sections;
isym < isymend;
isym++, pindex++, ppsection++)
@ -11457,7 +11457,7 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
irela = internal_relocs;
irelaend = irela + o->reloc_count;
rel_hash = esdo->rel.hashes + esdo->rel.count;
rel_hash = PTR_ADD (esdo->rel.hashes, esdo->rel.count);
/* We start processing the REL relocs, if any. When we reach
IRELAMID in the loop, we switch to the RELA relocs. */
irelamid = irela;
@ -11483,7 +11483,7 @@ elf_link_input_bfd (struct elf_final_link_info *flinfo, bfd *input_bfd)
if (irela == irelamid)
{
rel_hash = esdo->rela.hashes + esdo->rela.count;
rel_hash = PTR_ADD (esdo->rela.hashes, esdo->rela.count);
rela_hash_list = rel_hash;
rela_normal = bed->rela_normal;
}
@ -12957,7 +12957,7 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
BFD_ASSERT (o != NULL);
dyncon = o->contents;
dynconend = o->contents + o->size;
dynconend = PTR_ADD (o->contents, o->size);
for (; dyncon < dynconend; dyncon += bed->s->sizeof_dyn)
{
Elf_Internal_Dyn dyn;
@ -13160,7 +13160,8 @@ bfd_elf_final_link (bfd *abfd, struct bfd_link_info *info)
/* Check for DT_TEXTREL (late, in case the backend removes it). */
if (bfd_link_textrel_check (info)
&& (o = bfd_get_linker_section (dynobj, ".dynamic")) != NULL)
&& (o = bfd_get_linker_section (dynobj, ".dynamic")) != NULL
&& o->size != 0)
{
bfd_byte *dyncon, *dynconend;
@ -14206,7 +14207,7 @@ bfd_elf_gc_record_vtinherit (bfd *abfd,
extsymcount -= elf_tdata (abfd)->symtab_hdr.sh_info;
sym_hashes = elf_sym_hashes (abfd);
sym_hashes_end = sym_hashes + extsymcount;
sym_hashes_end = PTR_ADD (sym_hashes, extsymcount);
/* Hunt down the child symbol, which is in this section at the same
offset as the relocation. */

2
binutils/objdump.c
View file

@ -3208,7 +3208,7 @@ disassemble_section (bfd *abfd, asection *section, void *inf)
}
}
}
rel_ppend = rel_pp + rel_count;
rel_ppend = PTR_ADD (rel_pp, rel_count);
if (!bfd_malloc_and_get_section (abfd, section, &data))
{