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author | Alan Modra <amodra@gmail.com> | 2019-11-26 16:49:44 +1030 |
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committer | Alan Modra <amodra@gmail.com> | 2019-12-26 17:49:03 +1030 |
commit | 8ce18f9cdf53c846e0486130a66ba55c96fc2b14 (patch) | |
tree | 00869e348fe72b0b9165e3858861254b9489fc37 /ld/ldelf.c | |
parent | 100b122fc125bdf1fe768a3331a0cd413c3d1261 (diff) | |
download | binutils-8ce18f9cdf53c846e0486130a66ba55c96fc2b14.zip binutils-8ce18f9cdf53c846e0486130a66ba55c96fc2b14.tar.gz binutils-8ce18f9cdf53c846e0486130a66ba55c96fc2b14.tar.bz2 |
Avoid ubsan bug complaining about &p->field
I reckon it's quite OK to write &p->field in C when p might be NULL,
and lots of old C programmers probably agree with me. However, ubsan
disagrees and so do some people I respect. I suspect C++ influence is
to blame for the ubsan behaviour. See
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=92634. So far no one has
educated me as to why I'm wrong to claim that there isn't anything in
the C standard to say that p->field is always (*p).field. Note 79
doesn't quite do that because it doesn't cover null pointers. If
there was such an equivalence then you could claim &p->field has a
null pointer reference when p is NULL, even though no C compiler would
ever dereference p.
Anyway, to silence ubsan I'm going to apply the following though I
prefer to avoid casts when possible. And I'm using (void *)
deliberately because this is C, not C++!
* ldlang.c (lang_output_section_find_by_flags): Don't use &p->field
when p might be NULL.
* ldelf.c (output_rel_find, ldelf_place_orphan): Likewise.
(insert_os_after, lang_insert_orphan, lookup_name): Likewise.
(strip_excluded_output_sections, lang_clear_os_map): Likewise.
(lang_check, lang_for_each_input_file): Likewise.
(lang_reset_memory_regions, find_replacements_insert_point): Likewise.
(find_rescan_insertion, lang_propagate_lma_regions): Likewise.
(lang_record_phdrs): Likewise.
* emultempl/alphaelf.em (alpha_after_open): Likewise.
* emultempl/mmo.em (mmo_place_orphan): Likewise.
* emultempl/pe.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
* emultempl/pep.em (gld_${EMULATION_NAME}_place_orphan): Likewise.
* emultempl/ppc32elf.em (ppc_after_check_relocs): Likewise.
* emultempl/spuelf.em (spu_before_allocation): Likewise.
(embedded_spu_file): Likewise.
Diffstat (limited to 'ld/ldelf.c')
-rw-r--r-- | ld/ldelf.c | 6 |
1 files changed, 3 insertions, 3 deletions
@@ -1780,7 +1780,7 @@ output_rel_find (int isdyn, int rela) lang_output_section_statement_type *last_rel = NULL; lang_output_section_statement_type *last_rel_alloc = NULL; - for (lookup = &lang_os_list.head->output_section_statement; + for (lookup = (void *) lang_os_list.head; lookup != NULL; lookup = lookup->next) { @@ -1952,7 +1952,7 @@ ldelf_place_orphan (asection *s, const char *secname, int constraint) { /* Find the output mbind section with the same type, attributes and sh_info field. */ - for (os = &lang_os_list.head->output_section_statement; + for (os = (void *) lang_os_list.head; os != NULL; os = os->next) if (os->bfd_section != NULL @@ -2129,7 +2129,7 @@ ldelf_place_orphan (asection *s, const char *secname, int constraint) _bfd_elf_match_sections_by_type); if (after == NULL) /* *ABS* is always the first output section statement. */ - after = &lang_os_list.head->output_section_statement; + after = (void *) lang_os_list.head; } return lang_insert_orphan (s, secname, constraint, after, place, NULL, NULL); |