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LoongArch: overflow and underflow checks for R_LARCH_32_PCREL

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Relocation overflows can silently write incorrect value to
the file, so overflow checks are added to avoid this.
This commit is contained in:
Lulu Cai
2025-05-20 19:38:12 +08:00
committed by cailulu
parent 378d39e87f
commit 95d54e0c6e
6 changed files with 32 additions and 6 deletions
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20
bfd/elfnn-loongarch.c
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@@ -2933,11 +2933,21 @@ perform_relocation (const Elf_Internal_Rela *rel, asection *input_section,
{ {
value -= sec_addr (input_section) + rel->r_offset; value -= sec_addr (input_section) + rel->r_offset;
value += rel->r_addend; value += rel->r_addend;
bfd_vma word = bfd_get (howto->bitsize, input_bfd, /* Check overflow. */
contents + rel->r_offset); if (ELFNN_R_TYPE (rel->r_info) == R_LARCH_32_PCREL)
word = (word & ~howto->dst_mask) | (value & howto->dst_mask); {
bfd_put (howto->bitsize, input_bfd, word, contents + rel->r_offset); r = loongarch_reloc_rewrite_imm_insn (rel, input_section,
r = bfd_reloc_ok; howto, input_bfd,
contents, value);
}
else
{
bfd_vma word = bfd_get (howto->bitsize, input_bfd,
contents + rel->r_offset);
word = (word & ~howto->dst_mask) | (value & howto->dst_mask);
bfd_put (howto->bitsize, input_bfd, word, contents + rel->r_offset);
r = bfd_reloc_ok;
}
break; break;
} }

2
bfd/elfxx-loongarch.c
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@@ -1390,7 +1390,7 @@ static loongarch_reloc_howto_type loongarch_howto_table[] =
0xffffffff, /* dst_mask */ 0xffffffff, /* dst_mask */
false, /* pcrel_offset */ false, /* pcrel_offset */
BFD_RELOC_LARCH_32_PCREL, /* bfd_reloc_code_real_type */ BFD_RELOC_LARCH_32_PCREL, /* bfd_reloc_code_real_type */
NULL, /* adjust_reloc_bits */ reloc_sign_bits, /* adjust_reloc_bits */
NULL), /* larch_reloc_type_name */ NULL), /* larch_reloc_type_name */
/* The paired relocation may be relaxed. */ /* The paired relocation may be relaxed. */

6
ld/testsuite/ld-loongarch-elf/32_pcrel.s Normal file
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@@ -0,0 +1,6 @@
.section sx,"a"
x:
nop
.section sy,"a"
.4byte x-.

2
ld/testsuite/ld-loongarch-elf/ld-loongarch-elf.exp
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@@ -200,6 +200,8 @@ if [istarget "loongarch64-*-*"] {
run_dump_test "bad_pcrel20_s2_global" run_dump_test "bad_pcrel20_s2_global"
run_dump_test "bad_pcrel20_s2_weak" run_dump_test "bad_pcrel20_s2_weak"
run_dump_test "weak-undef-hidden-shared" run_dump_test "weak-undef-hidden-shared"
run_dump_test "overflow_32_pcrel"
run_dump_test "underflow_32_pcrel"
} }
if [check_pie_support] { if [check_pie_support] {

4
ld/testsuite/ld-loongarch-elf/overflow_32_pcrel.d Normal file
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@@ -0,0 +1,4 @@
#source: 32_pcrel.s
#as: -mthin-add-sub
#ld: -shared --section-start=sx=0x80001000 --section-start=sy=0x1000
#error: .*relocation truncated to fit: R_LARCH_32_PCREL against `x'

4
ld/testsuite/ld-loongarch-elf/underflow_32_pcrel.d Normal file
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@@ -0,0 +1,4 @@
#source: 32_pcrel.s
#as: -mthin-add-sub
#ld: -shared --section-start=sx=0x1000 --section-start=sy=0x80001001
#error: .*relocation truncated to fit: R_LARCH_32_PCREL against `x'