Protect mips_hi16_list from fuzzed debug info
Alan Modra
amodra@gmail.com
Mon Feb 6 12:33:09 GMT 2023
This is another fix for the testcase mentioned in
https://sourceware.org/pipermail/binutils/2023-February/125915.html
either of which will stop the addr2line segfault. This one also fixes
a potential problem when linking corrupted debug info.
OK to apply?
* elfxx-mips.c (struct mips_elf_obj_tdata): Add freeze_mips_hi16_list.
(_bfd_mips_elf_hi16_reloc): Heed freeze_mips_hi16_list.
(_bfd_mips_elf_lo16_reloc): Likewise.
(find_nearest_line): Rename from _bfd_mips_elf_find_nearest_line
and make static.
(_bfd_mips_elf_find_nearest_line): New wrapper function setting
freeze_mips_hi16_list around find_nearest_line.
diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c
index e9fb61ff9e7..20934c477e2 100644
--- a/bfd/elfxx-mips.c
+++ b/bfd/elfxx-mips.c
@@ -599,6 +599,7 @@ struct mips_elf_obj_tdata
asection *elf_text_section;
struct mips_hi16 *mips_hi16_list;
+ bool freeze_mips_hi16_list;
};
/* Get MIPS ELF private object data from BFD's tdata. */
@@ -2534,11 +2535,14 @@ _bfd_mips_elf_hi16_reloc (bfd *abfd, arelent *reloc_entry,
if (reloc_entry->address > bfd_get_section_limit (abfd, input_section))
return bfd_reloc_outofrange;
+ tdata = mips_elf_tdata (abfd);
+ if (tdata->freeze_mips_hi16_list)
+ return bfd_reloc_outofrange;
+
n = bfd_malloc (sizeof *n);
if (n == NULL)
return bfd_reloc_outofrange;
- tdata = mips_elf_tdata (abfd);
n->next = tdata->mips_hi16_list;
n->data = data;
n->input_section = input_section;
@@ -2596,38 +2600,41 @@ _bfd_mips_elf_lo16_reloc (bfd *abfd, arelent *reloc_entry, asymbol *symbol,
location);
tdata = mips_elf_tdata (abfd);
- while (tdata->mips_hi16_list != NULL)
- {
- bfd_reloc_status_type ret;
- struct mips_hi16 *hi;
-
- hi = tdata->mips_hi16_list;
-
- /* R_MIPS*_GOT16 relocations are something of a special case. We
- want to install the addend in the same way as for a R_MIPS*_HI16
- relocation (with a rightshift of 16). However, since GOT16
- relocations can also be used with global symbols, their howto
- has a rightshift of 0. */
- if (hi->rel.howto->type == R_MIPS_GOT16)
- hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MIPS_HI16, false);
- else if (hi->rel.howto->type == R_MIPS16_GOT16)
- hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MIPS16_HI16, false);
- else if (hi->rel.howto->type == R_MICROMIPS_GOT16)
- hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MICROMIPS_HI16, false);
-
- /* VALLO is a signed 16-bit number. Bias it by 0x8000 so that any
- carry or borrow will induce a change of +1 or -1 in the high part. */
- hi->rel.addend += (vallo + 0x8000) & 0xffff;
-
- ret = _bfd_mips_elf_generic_reloc (abfd, &hi->rel, symbol, hi->data,
- hi->input_section, output_bfd,
- error_message);
- if (ret != bfd_reloc_ok)
- return ret;
-
- tdata->mips_hi16_list = hi->next;
- free (hi);
- }
+ if (!tdata->freeze_mips_hi16_list)
+ while (tdata->mips_hi16_list != NULL)
+ {
+ bfd_reloc_status_type ret;
+ struct mips_hi16 *hi;
+
+ hi = tdata->mips_hi16_list;
+
+ /* R_MIPS*_GOT16 relocations are something of a special case.
+ We want to install the addend in the same way as for a
+ R_MIPS*_HI16 relocation (with a rightshift of 16).
+ However, since GOT16 relocations can also be used with
+ global symbols, their howto has a rightshift of 0. */
+ if (hi->rel.howto->type == R_MIPS_GOT16)
+ hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MIPS_HI16, false);
+ else if (hi->rel.howto->type == R_MIPS16_GOT16)
+ hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MIPS16_HI16, false);
+ else if (hi->rel.howto->type == R_MICROMIPS_GOT16)
+ hi->rel.howto = MIPS_ELF_RTYPE_TO_HOWTO (abfd, R_MICROMIPS_HI16,
+ false);
+
+ /* VALLO is a signed 16-bit number. Bias it by 0x8000 so that
+ any carry or borrow will induce a change of +1 or -1 in the
+ high part. */
+ hi->rel.addend += (vallo + 0x8000) & 0xffff;
+
+ ret = _bfd_mips_elf_generic_reloc (abfd, &hi->rel, symbol, hi->data,
+ hi->input_section, output_bfd,
+ error_message);
+ if (ret != bfd_reloc_ok)
+ return ret;
+
+ tdata->mips_hi16_list = hi->next;
+ free (hi);
+ }
return _bfd_mips_elf_generic_reloc (abfd, reloc_entry, symbol, data,
input_section, output_bfd,
@@ -13118,13 +13125,11 @@ struct mips_elf_find_line
struct ecoff_find_line i;
};
-bool
-_bfd_mips_elf_find_nearest_line (bfd *abfd, asymbol **symbols,
- asection *section, bfd_vma offset,
- const char **filename_ptr,
- const char **functionname_ptr,
- unsigned int *line_ptr,
- unsigned int *discriminator_ptr)
+static bool
+find_nearest_line (bfd *abfd, asymbol **symbols,
+ asection *section, bfd_vma offset,
+ const char **filename_ptr, const char **functionname_ptr,
+ unsigned int *line_ptr, unsigned int *discriminator_ptr)
{
asection *msec;
@@ -13228,6 +13233,25 @@ _bfd_mips_elf_find_nearest_line (bfd *abfd, asymbol **symbols,
line_ptr, discriminator_ptr);
}
+bool
+_bfd_mips_elf_find_nearest_line (bfd *abfd, asymbol **symbols,
+ asection *section, bfd_vma offset,
+ const char **filename_ptr,
+ const char **functionname_ptr,
+ unsigned int *line_ptr,
+ unsigned int *discriminator_ptr)
+{
+ /* Debug info should not contain hi16 or lo16 relocs. If it does
+ then someone is playing fuzzing games. Altering the hi16 list
+ during linking when printing an error message is bad. */
+ mips_elf_tdata (abfd)->freeze_mips_hi16_list = true;
+ bool ret = find_nearest_line (abfd, symbols, section, offset,
+ filename_ptr, functionname_ptr,
+ line_ptr, discriminator_ptr);
+ mips_elf_tdata (abfd)->freeze_mips_hi16_list = false;
+ return ret;
+}
+
bool
_bfd_mips_elf_find_inliner_info (bfd *abfd,
const char **filename_ptr,
@@ -13321,16 +13345,19 @@ _bfd_elf_mips_get_relocated_section_contents
mips_hi16_list that point into this section's data. Data
will typically be freed on return from this function. */
tdata = mips_elf_tdata (abfd);
- hip = &tdata->mips_hi16_list;
- while ((hi = *hip) != NULL)
+ if (!tdata->freeze_mips_hi16_list)
{
- if (hi->input_section == input_section)
+ hip = &tdata->mips_hi16_list;
+ while ((hi = *hip) != NULL)
{
- *hip = hi->next;
- free (hi);
+ if (hi->input_section == input_section)
+ {
+ *hip = hi->next;
+ free (hi);
+ }
+ else
+ hip = &hi->next;
}
- else
- hip = &hi->next;
}
if (orig_data == NULL)
free (data);
--
Alan Modra
Australia Development Lab, IBM
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