1388893 - Elfhack potential nullptr access

Status: RESOLVED FIXED

(Firefox Build System :: General, enhancement)

Description

[Eugen Sawin [:esawin]]

Coverity Scan has picked up the following defect:

*** CID 162741:    (FORWARD_NULL)
/build/unix/elfhack/elfhack.cpp: 757 in do_relocation_section<Elf_Rela>(Elf *, unsigned int, unsigned int, bool, bool)()
751         section->rels.assign(new_rels.begin(), new_rels.end());
752         section->shrink(new_rels.size() * section->getEntSize());
753
754         ElfRelHackCode_Section *relhackcode = new ElfRelHackCode_Section(relhackcode_section, *elf, *relhack, original_init, mprotect_cb);
755         // Find the first executable section, and insert the relhack code before
756         // that. The relhack data is inserted between .rel.dyn and .rel.plt.
>>>     CID 162741:    (FORWARD_NULL)
>>>     Assigning: "first_executable" = "NULL".
757         ElfSection *first_executable = nullptr;
758         for (ElfSection *s = elf->getSection(1); s != nullptr;
759              s = s->getNext()) {
760             if (s->getFlags() & SHF_EXECINSTR) {
761                 first_executable = s;
762                 break;
/build/unix/elfhack/elfhack.cpp: 757 in do_relocation_section<Elf_Rel>(Elf *, unsigned int, unsigned int, bool, bool)()
751         section->rels.assign(new_rels.begin(), new_rels.end());
752         section->shrink(new_rels.size() * section->getEntSize());
753
754         ElfRelHackCode_Section *relhackcode = new ElfRelHackCode_Section(relhackcode_section, *elf, *relhack, original_init, mprotect_cb);
755         // Find the first executable section, and insert the relhack code before
756         // that. The relhack data is inserted between .rel.dyn and .rel.plt.
>>>     CID 162741:    (FORWARD_NULL)
>>>     Assigning: "first_executable" = "NULL".
757         ElfSection *first_executable = nullptr;
758         for (ElfSection *s = elf->getSection(1); s != nullptr;
759              s = s->getNext()) {
760             if (s->getFlags() & SHF_EXECINSTR) {
761                 first_executable = s;
762                 break;

Comment 1

[Eugen Sawin [:esawin]]

Attachment: 0001-Bug-1388893-1.0-Abort-code-insertion-if-executable-s.patch

Comment 2

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/mozilla-inbound/rev/f6d10bc8c36c
[1.0] Abort code insertion if executable section was not found. r=glandium

Comment 3

[Wes Kocher (:KWierso) (Not reading bugmail; email directly if needed)]

https://hg.mozilla.org/mozilla-central/rev/f6d10bc8c36c