[v11,4/7] elf: Properly handle zero DT_RELA/DT_REL values
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Patch applied to master at the time it was sent
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Commit Message
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 | 24 ++++++++++++++++++------
2 files changed, 23 insertions(+), 7 deletions(-)
Comments
On 2022-04-22, H.J. Lu wrote:
>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 | 24 ++++++++++++++++++------
> 2 files changed, 23 insertions(+), 7 deletions(-)
>
>diff --git a/elf/dynamic-link.h b/elf/dynamic-link.h
>index 019088f248..debbb8c9f7 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] != NULL \
>+ && (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..0314baf020 100644
>--- a/elf/get-dynamic-info.h
>+++ b/elf/get-dynamic-info.h
>@@ -75,24 +75,36 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap,
>
> # define ADJUST_DYN_INFO(tag) \
> do \
>- if (info[tag] != NULL) \
>- info[tag]->d_un.d_ptr += l_addr; \
>+ { \
>+ if (info[tag] != NULL) \
>+ info[tag]->d_un.d_ptr += l_addr; \
>+ } \
> while (0)
>
> ADJUST_DYN_INFO (DT_HASH);
> 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)
>--
>2.35.1
>
LG, Thanks
Reviewed-by: Fangrui Song <maskray@google.com>
@@ -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] != NULL \
+ && (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) \
@@ -75,24 +75,36 @@ elf_get_dynamic_info (struct link_map *l, bool bootstrap,
# define ADJUST_DYN_INFO(tag) \
do \
- if (info[tag] != NULL) \
- info[tag]->d_un.d_ptr += l_addr; \
+ { \
+ if (info[tag] != NULL) \
+ info[tag]->d_un.d_ptr += l_addr; \
+ } \
while (0)
ADJUST_DYN_INFO (DT_HASH);
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)