public inbox for binutils@sourceware.org
 help / color / mirror / Atom feed
From: Xi Ruoyao <xry111@xry111.site>
To: binutils@sourceware.org
Cc: liuzhensong <liuzhensong@loongson.cn>,
	Lulu Cheng <chenglulu@loongson.cn>, Wang Xuerui <i@xen0n.name>,
	Chenghua Xu <xuchenghua@loongson.cn>,
	Xi Ruoyao <xry111@xry111.site>
Subject: [PATCH v2 1/2] LoongArch: Don't write into GOT for local ifunc
Date: Tue, 20 Sep 2022 14:09:29 +0800	[thread overview]
Message-ID: <20220920060930.33357-2-xry111@xry111.site> (raw)
In-Reply-To: <20220920060930.33357-1-xry111@xry111.site>

Local ifuncs are always resolved at runtime via R_LARCH_IRELATIVE, so
there is no need to write anything into GOT.  And when we write the GOT
we actually trigger a heap-buffer-overflow: If a and b are different
sections, we cannot access something in b with "a->contents + (offset
from a)" because "a->contents" and "b->contents" are heap buffers
allocated separately, not slices of a large buffer.

So stop writing into GOT for local ifunc now.
---
 bfd/elfnn-loongarch.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/bfd/elfnn-loongarch.c b/bfd/elfnn-loongarch.c
index ed42b8b6770..af18a8a0168 100644
--- a/bfd/elfnn-loongarch.c
+++ b/bfd/elfnn-loongarch.c
@@ -3179,6 +3179,8 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 						     htab->elf.srelgot, &rela);
 			}
 		      h->got.offset |= 1;
+		      bfd_put_NN (output_bfd, relocation,
+				  got->contents + got_off);
 		    }
 		}
 	      else
@@ -3200,10 +3202,9 @@ loongarch_elf_relocate_section (bfd *output_bfd, struct bfd_link_info *info,
 			}
 		      local_got_offsets[r_symndx] |= 1;
 		    }
+		  bfd_put_NN (output_bfd, relocation, got->contents + got_off);
 		}
 
-	      bfd_put_NN (output_bfd, relocation, got->contents + got_off);
-
 	      relocation = got_off + sec_addr (got);
 	    }
 
-- 
2.37.0


  reply	other threads:[~2022-09-20  6:10 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-09-20  6:09 [PATCH v2 0/2] Fix two bugs breaking IFUNC in static PIE Xi Ruoyao
2022-09-20  6:09 ` Xi Ruoyao [this message]
2022-09-20  6:09 ` [PATCH v2 2/2] LoongArch: Fix R_LARCH_IRELATIVE insertion after elf_link_sort_relocs Xi Ruoyao
2022-09-20  9:29 ` [PATCH v2 0/2] Fix two bugs breaking IFUNC in static PIE liuzhensong

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20220920060930.33357-2-xry111@xry111.site \
    --to=xry111@xry111.site \
    --cc=binutils@sourceware.org \
    --cc=chenglulu@loongson.cn \
    --cc=i@xen0n.name \
    --cc=liuzhensong@loongson.cn \
    --cc=xuchenghua@loongson.cn \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).