From 51a8a7c2e3cc0730831963651a55d23d1fae624d Mon Sep 17 00:00:00 2001 From: Nelson Chu Date: Tue, 6 Oct 2020 20:48:23 -0700 Subject: [PATCH] RISC-V: Fix that IRELATIVE relocs may be inserted to the wrong place. For the ifunc symbol, which is referenced by GOT rather than PLT relocs, we should add the dynamic reloc (usually IRELATIVE) into the .rel.iplt when generating the static executable. But if we use riscv_elf_append_rela to add the dynamic relocs into .rela.iplt, this may cause the overwrite problem. The reason is that we don't handle the `reloc_index` of .rela.iplt, but the riscv_elf_append_rela adds the relocs to the place that are calculated from the reloc_index (in seqential). Therefore, we may overwrite the dynamic relocs when the `reloc_index` of .rela.iplt isn't handled correctly. One solution is that we can add these dynamic relocs (GOT ifunc) from the last of .rela.iplt section. But I'm not sure if it is the best way. bfd/ * elfnn-riscv.c (riscv_elf_link_hash_table): Add last_iplt_index. (riscv_elf_size_dynamic_sections): Initialize the last_iplt_index. (riscv_elf_relocate_section): Use riscv_elf_append_rela. (riscv_elf_finish_dynamic_symbol): If the use_elf_append_rela is false, then we should add the dynamic relocs from the last of the .rela.iplt, and don't use the riscv_elf_append_rela to add. ld/ * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s: New testcase. * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd: Likewise. * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd: Likewise. * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated. --- bfd/ChangeLog | 9 ++++ bfd/elfnn-riscv.c | 46 ++++++++++++++++--- ld/ChangeLog | 9 ++++ .../ifunc-plt-got-overwrite-exe.rd | 4 ++ .../ifunc-plt-got-overwrite-pic.rd | 8 ++++ .../ifunc-plt-got-overwrite-pie.rd | 7 +++ .../ld-riscv-elf/ifunc-plt-got-overwrite.d | 19 ++++++++ .../ld-riscv-elf/ifunc-plt-got-overwrite.s | 38 +++++++++++++++ ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp | 7 +++ 9 files changed, 140 insertions(+), 7 deletions(-) create mode 100644 ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd create mode 100644 ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd create mode 100644 ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd create mode 100644 ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d create mode 100644 ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s diff --git a/bfd/ChangeLog b/bfd/ChangeLog index b0cd8b8ec51..7fb61814106 100644 --- a/bfd/ChangeLog +++ b/bfd/ChangeLog @@ -1,3 +1,12 @@ +2020-10-16 Nelson Chu + + * elfnn-riscv.c (riscv_elf_link_hash_table): Add last_iplt_index. + (riscv_elf_size_dynamic_sections): Initialize the last_iplt_index. + (riscv_elf_relocate_section): Use riscv_elf_append_rela. + (riscv_elf_finish_dynamic_symbol): If the use_elf_append_rela is + false, then we should add the dynamic relocs from the last of + the .rela.iplt, and don't use the riscv_elf_append_rela to add. + 2020-10-16 Nelson Chu * elfnn-riscv.c: Include "objalloc.h" since we need objalloc_alloc. diff --git a/bfd/elfnn-riscv.c b/bfd/elfnn-riscv.c index a26cd3f2a6f..a5b2c8a198c 100644 --- a/bfd/elfnn-riscv.c +++ b/bfd/elfnn-riscv.c @@ -120,6 +120,9 @@ struct riscv_elf_link_hash_table /* Used by local STT_GNU_IFUNC symbols. */ htab_t loc_hash_table; void * loc_hash_memory; + + /* The index of the last unused .rel.iplt slot. */ + bfd_vma last_iplt_index; }; @@ -1424,6 +1427,11 @@ riscv_elf_size_dynamic_sections (bfd *output_bfd, struct bfd_link_info *info) local ifunc symbols. */ htab_traverse (htab->loc_hash_table, allocate_local_ifunc_dynrelocs, info); + /* Used to resolve the dynamic relocs overwite problems when + generating static executable. */ + if (htab->elf.irelplt) + htab->last_iplt_index = htab->elf.irelplt->reloc_count - 1; + if (htab->elf.sgotplt) { struct elf_link_hash_entry *got; @@ -2904,6 +2912,7 @@ riscv_elf_finish_dynamic_symbol (bfd *output_bfd, asection *sgot; asection *srela; Elf_Internal_Rela rela; + bfd_boolean use_elf_append_rela = TRUE; /* This symbol has an entry in the GOT. Set it up. */ @@ -2920,12 +2929,18 @@ riscv_elf_finish_dynamic_symbol (bfd *output_bfd, if (h->plt.offset == (bfd_vma) -1) { /* STT_GNU_IFUNC is referenced without PLT. */ + if (htab->elf.splt == NULL) { - /* use .rel[a].iplt section to store .got relocations + /* Use .rela.iplt section to store .got relocations in static executable. */ srela = htab->elf.irelplt; + + /* Do not use riscv_elf_append_rela to add dynamic + relocs. */ + use_elf_append_rela = FALSE; } + if (SYMBOL_REFERENCES_LOCAL (info, h)) { info->callbacks->minfo (_("Local IFUNC function `%s' in %pB\n"), @@ -2973,14 +2988,14 @@ riscv_elf_finish_dynamic_symbol (bfd *output_bfd, return TRUE; } } - /* If this is a local symbol reference, we just want to emit a RELATIVE - reloc. This can happen if it is a -Bsymbolic link, or a pie link, or - the symbol was forced to be local because of a version file. - The entry in the global offset table will already have been - initialized in the relocate_section function. */ else if (bfd_link_pic (info) && SYMBOL_REFERENCES_LOCAL (info, h)) { + /* If this is a local symbol reference, we just want to emit + a RELATIVE reloc. This can happen if it is a -Bsymbolic link, + or a pie link, or the symbol was forced to be local because + of a version file. The entry in the global offset table will + already have been initialized in the relocate_section function. */ BFD_ASSERT((h->got.offset & 1) != 0); asection *sec = h->root.u.def.section; rela.r_info = ELFNN_R_INFO (0, R_RISCV_RELATIVE); @@ -2998,7 +3013,24 @@ riscv_elf_finish_dynamic_symbol (bfd *output_bfd, bfd_put_NN (output_bfd, 0, sgot->contents + (h->got.offset & ~(bfd_vma) 1)); - riscv_elf_append_rela (output_bfd, srela, &rela); + + if (use_elf_append_rela) + riscv_elf_append_rela (output_bfd, srela, &rela); + else + { + /* Use riscv_elf_append_rela to add the dynamic relocs into + .rela.iplt may cause the overwrite problems. Since we insert + the relocs for PLT didn't handle the reloc_index of .rela.iplt, + but the riscv_elf_append_rela adds the relocs to the place + that are calculated from the reloc_index (in seqential). + + One solution is that add these dynamic relocs (GOT IFUNC) + from the last of .rela.iplt section. */ + bfd_vma iplt_idx = htab->last_iplt_index--; + bfd_byte *loc = srela->contents + + iplt_idx * sizeof (ElfNN_External_Rela); + bed->s->swap_reloca_out (output_bfd, &rela, loc); + } } if (h->needs_copy) diff --git a/ld/ChangeLog b/ld/ChangeLog index 3a9d3810984..780bb4b5958 100644 --- a/ld/ChangeLog +++ b/ld/ChangeLog @@ -1,3 +1,12 @@ +2020-10-16 Nelson Chu + + * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s: New testcase. + * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d: Likewise. + * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd: Likewise. + * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd: Likewise. + * testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd: Likewise. + * testsuite/ld-riscv-elf/ld-riscv-elf.exp: Updated. + 2020-10-16 Nelson Chu * emulparams/elf32lriscv-defs.sh: Add IREL_IN_PLT. diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd new file mode 100644 index 00000000000..0de47a4009f --- /dev/null +++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-exe.rd @@ -0,0 +1,4 @@ +Relocation section '.rela.plt' at .* +[ ]+Offset[ ]+Info[ ]+Type[ ]+.* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_IRELATIVE[ ]+[0-9a-f]* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_IRELATIVE[ ]+[0-9a-f]* diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd new file mode 100644 index 00000000000..f65d789b0b8 --- /dev/null +++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pic.rd @@ -0,0 +1,8 @@ +Relocation section '.rela.got' at .* +[ ]+Offset[ ]+Info[ ]+Type[ ]+.* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_(32|64)[ ]+foo2\(\)[ ]+foo2 \+ 0 +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_(32|64)[ ]+foo1\(\)[ ]+foo1 \+ 0 +#... +Relocation section '.rela.plt' at .* +[ ]+Offset[ ]+Info[ ]+Type[ ]+.* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_JUMP_SLOT[ ]+foo1\(\)[ ]+foo1 \+ 0 diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd new file mode 100644 index 00000000000..32e66f0bd37 --- /dev/null +++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite-pie.rd @@ -0,0 +1,7 @@ +Relocation section '.rela.got' at .* +[ ]+Offset[ ]+Info[ ]+Type[ ]+.* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_IRELATIVE[ ]+[0-9a-f]* + +Relocation section '.rela.plt' at .* +[ ]+Offset[ ]+Info[ ]+Type[ ]+.* +[0-9a-f]+[ ]+[0-9a-f]+[ ]+R_RISCV_IRELATIVE[ ]+[0-9a-f]* diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d new file mode 100644 index 00000000000..333dea3ea3c --- /dev/null +++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.d @@ -0,0 +1,19 @@ +#... +Disassembly of section .plt: +#... +0+[0-9a-f]+ <(\*ABS\*\+0x[0-9a-f]+@plt|foo@plt|.plt)>: +#... +Disassembly of section .text: +#... +0+[0-9a-f]+ : +#... +0+[0-9a-f]+ : +.*:[ ]+[0-9a-f]+[ ]+auipc[ ]+.* +.*:[ ]+[0-9a-f]+[ ]+(lw|ld)[ ]+.*<(_GLOBAL_OFFSET_TABLE_.*|.*)> +.*:[ ]+[0-9a-f]+[ ]+auipc[ ]+.* +.*:[ ]+[0-9a-f]+[ ]+jalr[ ]+.*<(.*plt.*)> +.*:[ ]+[0-9a-f]+[ ]+auipc[ ]+.* +.*:[ ]+[0-9a-f]+[ ]+jalr[ ]+.*<(.*plt.*)> +.*:[ ]+[0-9a-f]+[ ]+auipc[ ]+.* +.*:[ ]+[0-9a-f]+[ ]+(lw|ld)[ ]+.*<(_GLOBAL_OFFSET_TABLE_.*|.*)> +#... diff --git a/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s new file mode 100644 index 00000000000..6c2f8e8c42e --- /dev/null +++ b/ld/testsuite/ld-riscv-elf/ifunc-plt-got-overwrite.s @@ -0,0 +1,38 @@ + .text + + .type foo_resolver, @function +foo_resolver: + ret + .size foo_resolver, .-foo_resolver + + .globl foo1 + .type foo1, %gnu_indirect_function + .set foo1, foo_resolver + + .globl foo2 + .type foo2, %gnu_indirect_function + .set foo2, foo_resolver + + .globl bar + .type bar, @function +bar: +.L1: + auipc x1, %got_pcrel_hi (foo1) +.ifdef __64_bit__ + ld x1, %pcrel_lo (.L1) (x1) +.else + lw x1, %pcrel_lo (.L1) (x1) +.endif + + call foo1 + call foo1@plt + +.L2: + auipc x2, %got_pcrel_hi (foo2) +.ifdef __64_bit__ + ld x2, %pcrel_lo (.L2) (x2) +.else + lw x2, %pcrel_lo (.L2) (x2) +.endif + ret + .size bar, .-bar diff --git a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp index b82e0921afd..9834041acf6 100644 --- a/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp +++ b/ld/testsuite/ld-riscv-elf/ld-riscv-elf.exp @@ -175,6 +175,13 @@ if [istarget "riscv*-*-*"] { run_dump_test_ifunc "ifunc-plt-02" rv64 exe run_dump_test_ifunc "ifunc-plt-02" rv64 pie run_dump_test_ifunc "ifunc-plt-02" rv64 pic + # Check the .rela.iplt overwrite issue. + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 exe + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 pie + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv32 pic + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 exe + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 pie + run_dump_test_ifunc "ifunc-plt-got-overwrite" rv64 pic # Setup shared libraries. run_ld_link_tests { -- 2.30.2