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PR29495, rewrite_elf_program_header looping
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This patch, in order of significance:
1) Replaces some macros with inline functions.
2) Those inline functions catch and avoid arithmetic overflows when
   comparing addresses.
3) When assigning sections to segments (IS_SECTION_IN_INPUT_SEGMENT)
   use bed->want_p_paddr_set_to_zero to decide whether lma vs p_paddr
   or vma vs p_vaddr should be tested.  When remapping, use the same
   test, and use is_note rather than the more restrictive
   IS_COREFILE_NOTE.

It's important that the later tests not be more restrictive.  If they
are it can lead to the situation triggered by the testcases, where a
section seemingly didn't fit and thus needed a new mapping.  It didn't
fit the new mapping either, and this repeated until memory exhausted.

	PR 29495
	* elf.c (SEGMENT_END, SECTION_SIZE, IS_CONTAINED_BY_VMA): Delete.
	(IS_CONTAINED_BY_LMA, IS_NOTE, IS_COREFILE_NOTE): Delete.
	(segment_size, segment_end, section_size): New inline function.
	(is_contained_by, is_note): Likewise.
	(rewrite_elf_program_header): Use new functions.
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@amodra
amodra committed Aug 16, 2022
1 parent 390ddd6 commit 45d9243
Showing 1 changed file with 75 additions and 65 deletions.
140 changes: 75 additions & 65 deletions bfd/elf.c
View file
Expand Up @@ -6886,6 +6886,66 @@ _bfd_elf_symbol_from_bfd_symbol (bfd *abfd, asymbol **asym_ptr_ptr)
return idx;
}

static inline bfd_vma
segment_size (Elf_Internal_Phdr *segment)
{
return (segment->p_memsz > segment->p_filesz
? segment->p_memsz : segment->p_filesz);
}


/* Returns the end address of the segment + 1. */
static inline bfd_vma
segment_end (Elf_Internal_Phdr *segment, bfd_vma start)
{
return start + segment_size (segment);
}

static inline bfd_size_type
section_size (asection *section, Elf_Internal_Phdr *segment)
{
if ((section->flags & SEC_HAS_CONTENTS) != 0
|| (section->flags & SEC_THREAD_LOCAL) == 0
|| segment->p_type == PT_TLS)
return section->size;
return 0;
}

/* Returns TRUE if the given section is contained within the given
segment. LMA addresses are compared against PADDR when
bed->want_p_paddr_set_to_zero is false, VMA against VADDR when true. */
static bool
is_contained_by (asection *section, Elf_Internal_Phdr *segment,
bfd_vma paddr, bfd_vma vaddr, unsigned int opb,
const struct elf_backend_data *bed)
{
bfd_vma seg_addr = !bed->want_p_paddr_set_to_zero ? paddr : vaddr;
bfd_vma addr = !bed->want_p_paddr_set_to_zero ? section->lma : section->vma;
bfd_vma octet;
if (_bfd_mul_overflow (addr, opb, &octet))
return false;
/* The third and fourth lines below are testing that the section end
address is within the segment. It's written this way to avoid
overflow. Add seg_addr + section_size to both sides of the
inequality to make it obvious. */
return (octet >= seg_addr
&& segment_size (segment) >= section_size (section, segment)
&& (octet - seg_addr
<= segment_size (segment) - section_size (section, segment)));
}

/* Handle PT_NOTE segment. */
static bool
is_note (Elf_Internal_Phdr *p, asection *s)
{
return (p->p_type == PT_NOTE
&& elf_section_type (s) == SHT_NOTE
&& (ufile_ptr) s->filepos >= p->p_offset
&& p->p_filesz >= s->size
&& ((ufile_ptr) s->filepos - p->p_offset
<= p->p_filesz - s->size));
}

/* Rewrite program header information. */

static bool
Expand Down Expand Up @@ -6914,47 +6974,6 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)

num_segments = elf_elfheader (ibfd)->e_phnum;

/* Returns the end address of the segment + 1. */
#define SEGMENT_END(segment, start) \
(start + (segment->p_memsz > segment->p_filesz \
? segment->p_memsz : segment->p_filesz))

#define SECTION_SIZE(section, segment) \
(((section->flags & (SEC_HAS_CONTENTS | SEC_THREAD_LOCAL)) \
!= SEC_THREAD_LOCAL || segment->p_type == PT_TLS) \
? section->size : 0)

/* Returns TRUE if the given section is contained within
the given segment. VMA addresses are compared. */
#define IS_CONTAINED_BY_VMA(section, segment, opb) \
(section->vma * (opb) >= segment->p_vaddr \
&& (section->vma * (opb) + SECTION_SIZE (section, segment) \
<= (SEGMENT_END (segment, segment->p_vaddr))))

/* Returns TRUE if the given section is contained within
the given segment. LMA addresses are compared. */
#define IS_CONTAINED_BY_LMA(section, segment, base, opb) \
(section->lma * (opb) >= base \
&& (section->lma + SECTION_SIZE (section, segment) / (opb) >= section->lma) \
&& (section->lma * (opb) + SECTION_SIZE (section, segment) \
<= SEGMENT_END (segment, base)))

/* Handle PT_NOTE segment. */
#define IS_NOTE(p, s) \
(p->p_type == PT_NOTE \
&& elf_section_type (s) == SHT_NOTE \
&& (bfd_vma) s->filepos >= p->p_offset \
&& ((bfd_vma) s->filepos + s->size \
<= p->p_offset + p->p_filesz))

/* Special case: corefile "NOTE" section containing regs, prpsinfo
etc. */
#define IS_COREFILE_NOTE(p, s) \
(IS_NOTE (p, s) \
&& bfd_get_format (ibfd) == bfd_core \
&& s->vma == 0 \
&& s->lma == 0)

/* The complicated case when p_vaddr is 0 is to handle the Solaris
linker, which generates a PT_INTERP section with p_vaddr and
p_memsz set to 0. */
Expand Down Expand Up @@ -6983,19 +7002,18 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)
8. PT_DYNAMIC should not contain empty sections at the beginning
(with the possible exception of .dynamic). */
#define IS_SECTION_IN_INPUT_SEGMENT(section, segment, bed, opb) \
((((segment->p_paddr \
? IS_CONTAINED_BY_LMA (section, segment, segment->p_paddr, opb) \
: IS_CONTAINED_BY_VMA (section, segment, opb)) \
(((is_contained_by (section, segment, segment->p_paddr, \
segment->p_vaddr, opb, bed) \
&& (section->flags & SEC_ALLOC) != 0) \
|| IS_NOTE (segment, section)) \
|| is_note (segment, section)) \
&& segment->p_type != PT_GNU_STACK \
&& (segment->p_type != PT_TLS \
|| (section->flags & SEC_THREAD_LOCAL)) \
&& (segment->p_type == PT_LOAD \
|| segment->p_type == PT_TLS \
|| (section->flags & SEC_THREAD_LOCAL) == 0) \
&& (segment->p_type != PT_DYNAMIC \
|| SECTION_SIZE (section, segment) > 0 \
|| section_size (section, segment) > 0 \
|| (segment->p_paddr \
? segment->p_paddr != section->lma * (opb) \
: segment->p_vaddr != section->vma * (opb)) \
Expand All @@ -7010,7 +7028,7 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)

/* Returns TRUE iff seg1 starts after the end of seg2. */
#define SEGMENT_AFTER_SEGMENT(seg1, seg2, field) \
(seg1->field >= SEGMENT_END (seg2, seg2->field))
(seg1->field >= segment_end (seg2, seg2->field))

/* Returns TRUE iff seg1 and seg2 overlap. Segments overlap iff both
their VMA address ranges and their LMA address ranges overlap.
Expand Down Expand Up @@ -7090,8 +7108,8 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)
{
/* Extend SEGMENT2 to include SEGMENT and then delete
SEGMENT. */
extra_length = (SEGMENT_END (segment, segment->p_vaddr)
- SEGMENT_END (segment2, segment2->p_vaddr));
extra_length = (segment_end (segment, segment->p_vaddr)
- segment_end (segment2, segment2->p_vaddr));

if (extra_length > 0)
{
Expand All @@ -7110,8 +7128,8 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)
{
/* Extend SEGMENT to include SEGMENT2 and then delete
SEGMENT2. */
extra_length = (SEGMENT_END (segment2, segment2->p_vaddr)
- SEGMENT_END (segment, segment->p_vaddr));
extra_length = (segment_end (segment2, segment2->p_vaddr)
- segment_end (segment, segment->p_vaddr));

if (extra_length > 0)
{
Expand Down Expand Up @@ -7311,11 +7329,9 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)

/* Match up the physical address of the segment with the
LMA address of the output section. */
if (IS_CONTAINED_BY_LMA (output_section, segment, map->p_paddr,
opb)
|| IS_COREFILE_NOTE (segment, section)
|| (bed->want_p_paddr_set_to_zero
&& IS_CONTAINED_BY_VMA (output_section, segment, opb)))
if (is_contained_by (output_section, segment, map->p_paddr,
map->p_paddr + map->p_vaddr_offset, opb, bed)
|| is_note (segment, section))
{
if (matching_lma == NULL
|| output_section->lma < matching_lma->lma)
Expand Down Expand Up @@ -7431,9 +7447,9 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)

BFD_ASSERT (output_section != NULL);

if (IS_CONTAINED_BY_LMA (output_section, segment, map->p_paddr,
opb)
|| IS_COREFILE_NOTE (segment, section))
if (is_contained_by (output_section, segment, map->p_paddr,
map->p_paddr + map->p_vaddr_offset, opb, bed)
|| is_note (segment, section))
{
if (map->count == 0)
{
Expand Down Expand Up @@ -7556,12 +7572,6 @@ rewrite_elf_program_header (bfd *ibfd, bfd *obfd, bfd_vma maxpagesize)
}
}

#undef SEGMENT_END
#undef SECTION_SIZE
#undef IS_CONTAINED_BY_VMA
#undef IS_CONTAINED_BY_LMA
#undef IS_NOTE
#undef IS_COREFILE_NOTE
#undef IS_SOLARIS_PT_INTERP
#undef IS_SECTION_IN_INPUT_SEGMENT
#undef INCLUDE_SECTION_IN_SEGMENT
Expand Down

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