From db841b6fcd8b3bc2e6d6774e81c14dfbb9ac815d Mon Sep 17 00:00:00 2001 From: "Maciej W. Rozycki" Date: Fri, 20 Jul 2018 13:21:33 +0100 Subject: [PATCH] MIPS/LD: Fix crashing with a discarded dynamic relocation section Fix a crash that occurs in `_bfd_mips_elf_finish_dynamic_sections' if a dynamic relocation section has been created, but marked to be discarded by an assignment to the /DISCARD/ output section in a linker script. In that case the output section is the absolute section, which has no ELF section data attached, so trying to set its `sh_size' parameter causes a null pointer dereference. This is only done as the value for the DT_RELSZ dynamic entry is being set, so fix the problem by not creating DT_REL, DT_RELSZ or DT_RELENT dynamic entries in the first place if the dynamic relocation section will not be output, as with no dynamic relocation data present these would not serve their purpose anyway. Add a generic ELF test case to verify that no dynamic relocation data is reported in the dynamic segment. bfd/ * elfxx-mips.c (_bfd_mips_elf_size_dynamic_sections): Do not create DT_REL, DT_RELSZ or DT_RELENT dynamic entries if the dynamic relocation section will be discarded from output. (_bfd_mips_elf_finish_dynamic_sections) : Assert that the dynamic relocation section will be retained in output. ld/ * testsuite/ld-elf/reloc-discard.d: New test. * testsuite/ld-elf/reloc-discard.ld: New test linker script. * testsuite/ld-elf/reloc-discard.s: New test source. --- bfd/ChangeLog | 8 ++++++++ bfd/elfxx-mips.c | 4 +++- ld/ChangeLog | 6 ++++++ ld/testsuite/ld-elf/reloc-discard.d | 10 ++++++++++ ld/testsuite/ld-elf/reloc-discard.ld | 6 ++++++ ld/testsuite/ld-elf/reloc-discard.s | 2 ++ 6 files changed, 35 insertions(+), 1 deletion(-) create mode 100644 ld/testsuite/ld-elf/reloc-discard.d create mode 100644 ld/testsuite/ld-elf/reloc-discard.ld create mode 100644 ld/testsuite/ld-elf/reloc-discard.s diff --git a/bfd/ChangeLog b/bfd/ChangeLog index c5960e61be4..9b7048c6001 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,11 @@ +2018-07-20 Maciej W. Rozycki + + * elfxx-mips.c (_bfd_mips_elf_size_dynamic_sections): Do not + create DT_REL, DT_RELSZ or DT_RELENT dynamic entries if the + dynamic relocation section will be discarded from output. + (_bfd_mips_elf_finish_dynamic_sections) : Assert that + the dynamic relocation section will be retained in output. + 2018-07-18 Maciej W. Rozycki * xcofflink.c (xcoff_write_global_symbol): Fix symbol type diff --git a/bfd/elfxx-mips.c b/bfd/elfxx-mips.c index d91942301c3..cc767ea6bf9 100644 --- a/bfd/elfxx-mips.c +++ b/bfd/elfxx-mips.c @@ -9890,7 +9890,8 @@ _bfd_mips_elf_size_dynamic_sections (bfd *output_bfd, } else { - if (sreldyn && sreldyn->size > 0) + if (sreldyn && sreldyn->size > 0 + && !bfd_is_abs_section (sreldyn->output_section)) { if (! MIPS_ELF_ADD_DYNAMIC_ENTRY (info, DT_REL, 0)) return FALSE; @@ -11798,6 +11799,7 @@ _bfd_mips_elf_finish_dynamic_sections (bfd *output_bfd, : sizeof (Elf32_External_Rel))); /* Adjust the section size too. Tools like the prelinker can reasonably expect the values to the same. */ + BFD_ASSERT (!bfd_is_abs_section (s->output_section)); elf_section_data (s->output_section)->this_hdr.sh_size = dyn.d_un.d_val; break; diff --git a/ld/ChangeLog b/ld/ChangeLog index c2f6b283589..8c7d2dfcb39 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,9 @@ +2018-07-20 Maciej W. Rozycki + + * testsuite/ld-elf/reloc-discard.d: New test. + * testsuite/ld-elf/reloc-discard.ld: New test linker script. + * testsuite/ld-elf/reloc-discard.s: New test source. + 2018-07-18 Nick Clifton * po/fr.po: Updated French translation. diff --git a/ld/testsuite/ld-elf/reloc-discard.d b/ld/testsuite/ld-elf/reloc-discard.d new file mode 100644 index 00000000000..b8aad886495 --- /dev/null +++ b/ld/testsuite/ld-elf/reloc-discard.d @@ -0,0 +1,10 @@ +#name: Discarded dynamic relocation section +#ld: -shared -T reloc-discard.ld +#readelf: -r --use-dynamic +#target: [check_shared_lib_support] +#source: reloc-discard.s +#xfail: nds32*-*-* tic6x-*-* +# Need to figure out how to pass `-fpic' for NDS32 or `-mpic -mpid=near' +# for TI C6X targets to GAS for this test. + +There are no dynamic relocations in this file\. diff --git a/ld/testsuite/ld-elf/reloc-discard.ld b/ld/testsuite/ld-elf/reloc-discard.ld new file mode 100644 index 00000000000..b16b80a2420 --- /dev/null +++ b/ld/testsuite/ld-elf/reloc-discard.ld @@ -0,0 +1,6 @@ +SECTIONS +{ + /* .dynamic needs to go first with MIPS IRIX-style emulations. */ + .dynamic : { *(.dynamic) } + /DISCARD/ : { *(.rel.dyn) *(.rela.dyn) } +} diff --git a/ld/testsuite/ld-elf/reloc-discard.s b/ld/testsuite/ld-elf/reloc-discard.s new file mode 100644 index 00000000000..23f187a126a --- /dev/null +++ b/ld/testsuite/ld-elf/reloc-discard.s @@ -0,0 +1,2 @@ + .data + .dc.a foo -- 2.30.2