[v6,2/5] 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 | 18 ++++++++++++++----
2 files changed, 19 insertions(+), 5 deletions(-)
Comments
On 10/03/2022 17:03, H.J. Lu via Libc-alpha 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.
Patch looks good with the two small fixes below.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
> ---
> 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 d04c457e55..252f407a12 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] \
Compare to NULL here.
> + && (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) \
Ok.
> 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)
> +
Maybe use '{' and '}' on the do ... while.
> # 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)
Ok.
On Tue, Mar 29, 2022 at 9:38 AM Adhemerval Zanella
<adhemerval.zanella@linaro.org> wrote:
>
>
>
> On 10/03/2022 17:03, H.J. Lu via Libc-alpha 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.
>
> Patch looks good with the two small fixes below.
>
> Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
>
> > ---
> > 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 d04c457e55..252f407a12 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] \
>
> Compare to NULL here.
Fixed in v7.
> > + && (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) \
>
> Ok.
>
> > 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)
> > +
>
> Maybe use '{' and '}' on the do ... while.
Fixed in v7.
> > # 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)
>
> Ok.
Thanks.
@@ -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) \
@@ -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)