From d2327e47ef26dc88192e07b53cbad0b768cecf2e Mon Sep 17 00:00:00 2001 From: Alan Modra Date: Tue, 25 Aug 2020 14:05:10 +0930 Subject: [PATCH] PR26422, ASAN: elf32_arm_final_link_relocate elf32-arm.c:10351 Always reading 32 bits in order to extract addends from instruction fields is wrong when the field size is smaller. It also leads to reading past the end of the section. This patch tidies that by reading the proper field size, which allows some later refetching of addends to disappear. PR 26422 * elf32-arm.c (elf32_arm_final_link_relocate): Use the appropriate bfd_get_x size function to read addends out of fields. Apply rightshift adjustment too. Don't apply the now unnecessary howto->size shift to branch REL addends. Don't refetch R_ARM_ABS8 and R_ARM_ABS16 addends. Don't refetch thumb branch addends. Correct R_ARM_THM_JUMP6 addend. --- bfd/ChangeLog | 10 ++++++++++ bfd/elf32-arm.c | 53 +++++++++++++++++-------------------------------- 2 files changed, 28 insertions(+), 35 deletions(-) diff --git a/bfd/ChangeLog b/bfd/ChangeLog index f1f0e322fe1..a24957a8c19 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,13 @@ +2020-08-25 Alan Modra + + PR 26422 + * elf32-arm.c (elf32_arm_final_link_relocate): Use the appropriate + bfd_get_x size function to read addends out of fields. Apply + rightshift adjustment too. Don't apply the now unnecessary + howto->size shift to branch REL addends. Don't refetch R_ARM_ABS8 + and R_ARM_ABS16 addends. Don't refetch thumb branch addends. + Correct R_ARM_THM_JUMP6 addend. + 2020-08-25 Alan Modra PR 26419 diff --git a/bfd/elf32-arm.c b/bfd/elf32-arm.c index 66930c0c7dc..8fec76e4e1d 100644 --- a/bfd/elf32-arm.c +++ b/bfd/elf32-arm.c @@ -10348,16 +10348,22 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, if (globals->use_rel) { - addend = bfd_get_32 (input_bfd, hit_data) & howto->src_mask; + bfd_vma sign; - if (addend & ((howto->src_mask + 1) >> 1)) + switch (howto->size) { - signed_addend = -1; - signed_addend &= ~ howto->src_mask; - signed_addend |= addend; + case 0: addend = bfd_get_8 (input_bfd, hit_data); break; + case 1: addend = bfd_get_16 (input_bfd, hit_data); break; + case 2: addend = bfd_get_32 (input_bfd, hit_data); break; + default: addend = 0; break; } - else - signed_addend = addend; + /* Note: the addend and signed_addend calculated here are + incorrect for any split field. */ + addend &= howto->src_mask; + sign = howto->src_mask & ~(howto->src_mask >> 1); + signed_addend = (addend ^ sign) - sign; + signed_addend = (bfd_vma) signed_addend << howto->rightshift; + addend <<= howto->rightshift; } else addend = signed_addend = rel->r_addend; @@ -10752,11 +10758,7 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, value -= (input_section->output_section->vma + input_section->output_offset); value -= rel->r_offset; - if (globals->use_rel) - value += (signed_addend << howto->size); - else - /* RELA addends do not have to be adjusted by howto->size. */ - value += signed_addend; + value += signed_addend; signed_addend = value; signed_addend >>= howto->rightshift; @@ -10860,9 +10862,6 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, return bfd_reloc_ok; case R_ARM_ABS8: - /* PR 16202: Refectch the addend using the correct size. */ - if (globals->use_rel) - addend = bfd_get_8 (input_bfd, hit_data); value += addend; /* There is no way to tell whether the user intended to use a signed or @@ -10875,9 +10874,6 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, return bfd_reloc_ok; case R_ARM_ABS16: - /* PR 16202: Refectch the addend using the correct size. */ - if (globals->use_rel) - addend = bfd_get_16 (input_bfd, hit_data); value += addend; /* See comment for R_ARM_ABS8. */ @@ -11356,25 +11352,12 @@ elf32_arm_final_link_relocate (reloc_howto_type * howto, /* CZB cannot jump backward. */ if (r_type == R_ARM_THM_JUMP6) - reloc_signed_min = 0; - - if (globals->use_rel) { - /* Need to refetch addend. */ - addend = bfd_get_16 (input_bfd, hit_data) & howto->src_mask; - if (addend & ((howto->src_mask + 1) >> 1)) - { - signed_addend = -1; - signed_addend &= ~ howto->src_mask; - signed_addend |= addend; - } - else - signed_addend = addend; - /* The value in the insn has been right shifted. We need to - undo this, so that we can perform the address calculation - in terms of bytes. */ - signed_addend <<= howto->rightshift; + reloc_signed_min = 0; + if (globals->use_rel) + signed_addend = ((addend & 0x200) >> 3) | ((addend & 0xf8) >> 2); } + relocation = value + signed_addend; relocation -= (input_section->output_section->vma -- 2.30.2