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authorNick Alcock <nick.alcock@oracle.com>2020-06-09 10:27:57 +0100
committerNick Alcock <nick.alcock@oracle.com>2020-07-22 18:02:18 +0100
commitd50c08025d41b2efc70dbb384fc691f2d9632463 (patch)
treef32f5a1ea26d5cedd9d159135ea48a16aa3f4d94 /libctf/ctf-open-bfd.c
parent70447401740235d828c4b7b87e398eeae4801094 (diff)
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libctf, open: fix opening CTF in binaries with no symtab
This is a perfectly possible case, and half of ctf_bfdopen_ctfsect handled it fine. The other half hit a divide by zero or two before we got that far, and had no code path to load the strtab from anywhere in the absence of a symtab to point at it in any case. So, as a fallback, if there is no symtab, try loading ".strtab" explicitly by name, like we used to before we started looking for the strtab the symtab used. Of course, such a strtab is not kept hold of by BFD, so this means we have to bring back the code to possibly explicitly free the strtab that we read in. libctf/ * ctf-impl.h (struct ctf_archive_internal) <ctfi_free_strsect> New. * ctf-open-bfd.c (ctf_bfdopen_ctfsect): Explicitly open a strtab if the input has no symtab, rather than dividing by zero. Arrange to free it later via ctfi_free_ctfsect. * ctf-archive.c (ctf_new_archive_internal): Do not ctfi_free_strsect by default. (ctf_arc_close): Possibly free it here.
Diffstat (limited to 'libctf/ctf-open-bfd.c')
-rw-r--r--libctf/ctf-open-bfd.c81
1 files changed, 55 insertions, 26 deletions
diff --git a/libctf/ctf-open-bfd.c b/libctf/ctf-open-bfd.c
index 2d2d572..9fcce2f 100644
--- a/libctf/ctf-open-bfd.c
+++ b/libctf/ctf-open-bfd.c
@@ -94,46 +94,69 @@ ctf_bfdopen_ctfsect (struct bfd *abfd _libctf_unused_,
ctf_sect_t *symsectp = NULL;
ctf_sect_t *strsectp = NULL;
const char *bfderrstr = NULL;
+ char *strtab_alloc = NULL;
#ifdef HAVE_BFD_ELF
ctf_sect_t symsect, strsect;
- Elf_Internal_Shdr *strhdr;
Elf_Internal_Shdr *symhdr = &elf_symtab_hdr (abfd);
- size_t symcount = symhdr->sh_size / symhdr->sh_entsize;
+ size_t symcount;
Elf_Internal_Sym *isymbuf;
- bfd_byte *symtab;
+ bfd_byte *symtab = NULL;
const char *strtab = NULL;
+ size_t strsize;
/* TODO: handle SYMTAB_SHNDX. */
- if ((symtab = malloc (symhdr->sh_size)) == NULL)
+ /* Get the symtab, and the strtab associated with it. */
+ if (elf_tdata (abfd) && symhdr && symhdr->sh_size && symhdr->sh_entsize)
{
- bfderrstr = "Cannot malloc symbol table";
- goto err;
- }
+ symcount = symhdr->sh_size / symhdr->sh_entsize;
+ if ((symtab = malloc (symhdr->sh_size)) == NULL)
+ {
+ bfderrstr = "Cannot malloc symbol table";
+ goto err;
+ }
- isymbuf = bfd_elf_get_elf_syms (abfd, symhdr, symcount, 0,
- NULL, symtab, NULL);
- free (isymbuf);
- if (isymbuf == NULL)
- {
- bfderrstr = "Cannot read symbol table";
- goto err_free_sym;
- }
+ isymbuf = bfd_elf_get_elf_syms (abfd, symhdr, symcount, 0,
+ NULL, symtab, NULL);
+ free (isymbuf);
+ if (isymbuf == NULL)
+ {
+ bfderrstr = "Cannot read symbol table";
+ goto err_free_sym;
+ }
+
+ if (elf_elfsections (abfd) != NULL
+ && symhdr->sh_link < elf_numsections (abfd))
+ {
+ Elf_Internal_Shdr *strhdr = elf_elfsections (abfd)[symhdr->sh_link];
- if (elf_elfsections (abfd) != NULL
- && symhdr->sh_link < elf_numsections (abfd))
+ strsize = strhdr->sh_size;
+ if (strhdr->contents == NULL)
+ {
+ if ((strtab = bfd_elf_get_str_section (abfd, symhdr->sh_link)) == NULL)
+ {
+ bfderrstr = "Cannot read string table";
+ goto err_free_sym;
+ }
+ }
+ else
+ strtab = (const char *) strhdr->contents;
+ }
+ }
+ else /* No symtab: just try getting .strtab by name. */
{
- strhdr = elf_elfsections (abfd)[symhdr->sh_link];
- if (strhdr->contents == NULL)
+ bfd_byte *str_bcontents;
+ asection *str_asect;
+
+ if ((str_asect = bfd_get_section_by_name (abfd, ".strtab")) != NULL)
{
- if ((strtab = bfd_elf_get_str_section (abfd, symhdr->sh_link)) == NULL)
+ if (bfd_malloc_and_get_section (abfd, str_asect, &str_bcontents))
{
- bfderrstr = "Cannot read string table";
- goto err_free_sym;
+ strtab = (const char *) str_bcontents;
+ strtab_alloc = (char *) str_bcontents;
+ strsize = str_asect->size;
}
}
- else
- strtab = (const char *) strhdr->contents;
}
if (strtab)
@@ -144,9 +167,12 @@ ctf_bfdopen_ctfsect (struct bfd *abfd _libctf_unused_,
strsect.cts_data = strtab;
strsect.cts_name = ".strtab";
- strsect.cts_size = strhdr->sh_size;
+ strsect.cts_size = strsize;
strsectp = &strsect;
+ }
+ if (symtab)
+ {
assert (symhdr->sh_entsize == get_elf_backend_data (abfd)->s->sizeof_sym);
symsect.cts_name = ".symtab";
symsect.cts_entsize = symhdr->sh_entsize;
@@ -159,13 +185,16 @@ ctf_bfdopen_ctfsect (struct bfd *abfd _libctf_unused_,
arci = ctf_arc_bufopen (ctfsect, symsectp, strsectp, errp);
if (arci)
{
- /* Request freeing of the symsect. */
+ /* Request freeing of the symsect and possibly the strsect. */
arci->ctfi_free_symsect = 1;
+ if (strtab_alloc)
+ arci->ctfi_free_strsect = 1;
return arci;
}
#ifdef HAVE_BFD_ELF
err_free_sym:
free (symtab);
+ free (strtab_alloc);
#endif
err: _libctf_unused_;
if (bfderrstr)