From: Xi Ruoyao <xry111@xry111.site>
To: liuzhensong <liuzhensong@loongson.cn>, binutils@sourceware.org
Cc: Chenghua Xu <xuchenghua@loongson.cn>,
Lulu Cheng <chenglulu@loongson.cn>, Wang Xuerui <i@xen0n.name>
Subject: Re: [PATCH 1/2] LoongArch: Avoid heap-buffer-overflow in loongarch_elf_relocate_section
Date: Wed, 14 Sep 2022 19:15:43 +0800 [thread overview]
Message-ID: <7f2c274b80fa79296005edaf52036745510a83fd.camel@xry111.site> (raw)
In-Reply-To: <a07e9df509c6171f004741fd4f9c943079585557.camel@xry111.site>
On Wed, 2022-09-14 at 18:15 +0800, Xi Ruoyao via Binutils wrote:
> > Shouldn't write to got table when using hidden ifunc.
>
> Perhaps it's true, using RELA to resolve a GOT entry should not depend
> on any "initial" value of the entry...
How about this? We don't need to write into the GOT if R_LARCH_RELATIVE
or R_LARCH_IRELATIVE will be used:
diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index a9bb66a1e04..1e8ecb2b8e2 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -3129,6 +3129,7 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
BFD_ASSERT (rel->r_addend == 0);
bfd_vma got_off = 0;
+ bool fill_got_entry = true;
if (h != NULL)
{
/* GOT ref or ifunc. */
@@ -3141,6 +3142,10 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
if (h->got.offset == MINUS_ONE && h->type == STT_GNU_IFUNC)
{
bfd_vma idx;
+
+ /* An IFUNC is always resolved at runtime. */
+ fill_got_entry = false;
+
if (htab->elf.splt != NULL)
{
idx = (h->plt.offset - PLT_HEADER_SIZE)
@@ -3177,6 +3182,7 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
rela.r_addend = relocation;
loongarch_elf_append_rela (output_bfd,
htab->elf.srelgot, &rela);
+ fill_got_entry = false;
}
h->got.offset |= 1;
}
@@ -3197,12 +3203,14 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
rela.r_addend = relocation;
loongarch_elf_append_rela (output_bfd,
htab->elf.srelgot, &rela);
+ fill_got_entry = false;
}
local_got_offsets[r_symndx] |= 1;
}
}
- bfd_put_NN (output_bfd, relocation, got->contents + got_off);
+ if (fill_got_entry)
+ bfd_put_NN (output_bfd, relocation, got->contents + got_off);
relocation = got_off + sec_addr (got);
}
--
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University
next prev parent reply other threads:[~2022-09-14 11:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-09-13 15:44 [PATCH 0/2] LoongArch: Fix two bugs breaking IFUNC in static PIE Xi Ruoyao
2022-09-13 15:44 ` [PATCH 1/2] LoongArch: Avoid heap-buffer-overflow in loongarch_elf_relocate_section Xi Ruoyao
2022-09-14 8:57 ` liuzhensong
2022-09-14 10:15 ` Xi Ruoyao
2022-09-14 11:15 ` Xi Ruoyao [this message]
2022-09-15 1:47 ` liuzhensong
2022-09-15 2:56 ` Xi Ruoyao
2022-09-15 3:54 ` liuzhensong
2022-09-15 6:13 ` Xi Ruoyao
2022-09-13 15:44 ` [PATCH 2/2] LoongArch: Fix R_LARCH_IRELATIVE insertion after elf_link_sort_relocs Xi Ruoyao
2022-09-15 13:03 ` liuzhensong
2022-09-16 20:11 ` Xi Ruoyao
2022-09-18 9:58 ` Xi Ruoyao
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