From: "H.J. Lu" <hjl.tools@gmail.com>
To: libc-alpha@sourceware.org
Cc: Fangrui Song <maskray@google.com>,
Joseph Myers <joseph@codesourcery.com>
Subject: [PATCH v3 2/5] elf: Properly handle zero DT_RELA/DT_REL values
Date: Mon, 7 Feb 2022 15:51:24 -0800 [thread overview]
Message-ID: <20220207235127.1807294-3-hjl.tools@gmail.com> (raw)
In-Reply-To: <20220207235127.1807294-1-hjl.tools@gmail.com>
With DT_RELR, there may be no relocations in DT_RELA/DT_REL and their
entry values are zero. Don't relocate DT_RELA/DT_REL and update the
combined relocation start address if their entry values are zero.
---
elf/dynamic-link.h | 6 +++++-
elf/get-dynamic-info.h | 18 ++++++++++++++----
2 files changed, 19 insertions(+), 5 deletions(-)
diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
index 5318079bac..320a9029f2 100644
--- a/elf/dynamic-link.h
+++ b/elf/dynamic-link.h
@@ -84,7 +84,9 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
__typeof (((ElfW(Dyn) *) 0)->d_un.d_val) nrelative; int lazy; } \
ranges[2] = { { 0, 0, 0, 0 }, { 0, 0, 0, 0 } }; \
\
- if ((map)->l_info[DT_##RELOC]) \
+ /* With DT_RELR, DT_RELA/DT_REL can have zero value. */ \
+ if ((map)->l_info[DT_##RELOC] \
+ && (map)->l_info[DT_##RELOC]->d_un.d_ptr != 0) \
{ \
ranges[0].start = D_PTR ((map), l_info[DT_##RELOC]); \
ranges[0].size = (map)->l_info[DT_##RELOC##SZ]->d_un.d_val; \
@@ -98,6 +100,8 @@ elf_machine_lazy_rel (struct link_map *map, struct r_scope_elem *scope[],
ElfW(Addr) start = D_PTR ((map), l_info[DT_JMPREL]); \
ElfW(Addr) size = (map)->l_info[DT_PLTRELSZ]->d_un.d_val; \
\
+ if (ranges[0].start == 0) \
+ ranges[0].start = start; \
if (ranges[0].start + ranges[0].size == (start + size)) \
ranges[0].size -= size; \
if (!(do_lazy) \
diff --git a/elf/get-dynamic-info.h b/elf/get-dynamic-info.h
index 6c2a3a12b1..f4b957684b 100644
--- a/elf/get-dynamic-info.h
+++ b/elf/get-dynamic-info.h
@@ -83,16 +83,26 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap,
ADJUST_DYN_INFO (DT_PLTGOT);
ADJUST_DYN_INFO (DT_STRTAB);
ADJUST_DYN_INFO (DT_SYMTAB);
+ ADJUST_DYN_INFO (DT_RELR);
+ ADJUST_DYN_INFO (DT_JMPREL);
+ ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM));
+ ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH));
+# undef ADJUST_DYN_INFO
+
+ /* DT_RELA/DT_REL are mandatory. But they may have zero value if
+ there is DT_RELR. Don't relocate them if they are zero. */
+# define ADJUST_DYN_INFO(tag) \
+ do \
+ if (info[tag] != NULL && info[tag]->d_un.d_ptr != 0) \
+ info[tag]->d_un.d_ptr += l_addr; \
+ while (0)
+
# if ! ELF_MACHINE_NO_RELA
ADJUST_DYN_INFO (DT_RELA);
# endif
# if ! ELF_MACHINE_NO_REL
ADJUST_DYN_INFO (DT_REL);
# endif
- ADJUST_DYN_INFO (DT_RELR);
- ADJUST_DYN_INFO (DT_JMPREL);
- ADJUST_DYN_INFO (VERSYMIDX (DT_VERSYM));
- ADJUST_DYN_INFO (ADDRIDX (DT_GNU_HASH));
# undef ADJUST_DYN_INFO
}
if (info[DT_PLTREL] != NULL)
--
2.34.1
next prev parent reply other threads:[~2022-02-07 23:51 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-02-07 23:51 [PATCH v3 0/5] Support DT_RELR relative relocation format H.J. Lu
2022-02-07 23:51 ` [PATCH v3 1/5] elf: Support DT_RELR relative relocation format [BZ #27924] H.J. Lu
2022-02-07 23:51 ` H.J. Lu [this message]
2022-02-07 23:51 ` [PATCH v3 3/5] Add GLIBC_ABI_DT_RELR for DT_RELR support H.J. Lu
2022-03-01 4:22 ` Fangrui Song
2022-03-01 14:42 ` H.J. Lu
2022-03-01 15:10 ` H.J. Lu
2022-03-01 19:13 ` Fangrui Song
2022-02-07 23:51 ` [PATCH v3 4/5] Add --disable-default-dt-relr H.J. Lu
2022-03-01 4:25 ` Fangrui Song
2022-02-07 23:51 ` [PATCH v3 5/5] NEWS: Mention DT_RELR support H.J. Lu
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