| Message ID | 20220623214932.4752-1-palmer@rivosinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | arm: Avoid UB in elf_machine_rel() | expand |
On 2022-06-23, Palmer Dabbelt wrote: >This recently came up during a cleanup to remove misaligned accesses >from the RISC-V port. > >Link: https://sourceware.org/pipermail/libc-alpha/2022-June/139961.html >Suggested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> >Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> LGTM Reviewed-by: Fangrui Song <maskray@google.com> >-- > >I haven't build this one, as I'm just doing it locally and don't have >everything setup here. >--- > sysdeps/arm/dl-machine.h | 9 ++++----- > 1 file changed, 4 insertions(+), 5 deletions(-) > >diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h >index 68dcb96d9d..6bb3917340 100644 >--- a/sysdeps/arm/dl-machine.h >+++ b/sysdeps/arm/dl-machine.h >@@ -402,10 +402,7 @@ elf_machine_rel (struct link_map *map, struct r_scope_elem *scope[], > break; > case R_ARM_ABS32: > { >- struct unaligned >- { >- Elf32_Addr x; >- } __attribute__ ((packed, may_alias)); >+ ElfW(Addr) tmp; > # ifndef RTLD_BOOTSTRAP > /* This is defined in rtld.c, but nowhere in the static > libc.a; make the reference weak so static programs can >@@ -425,7 +422,9 @@ elf_machine_rel (struct link_map *map, struct r_scope_elem *scope[], > value -= SYMBOL_ADDRESS (map, refsym, true); > # endif > /* Support relocations on mis-aligned offsets. */ >- ((struct unaligned *) reloc_addr)->x += value; >+ memcpy(&tmp, reloc_addr, sizeof tmp); >+ tmp += value; >+ memcpy (reloc_addr, &tmp, sizeof tmp); > break; > } > case R_ARM_TLS_DESC: >-- >2.34.1 >
diff --git a/sysdeps/arm/dl-machine.h b/sysdeps/arm/dl-machine.h index 68dcb96d9d..6bb3917340 100644 --- a/sysdeps/arm/dl-machine.h +++ b/sysdeps/arm/dl-machine.h @@ -402,10 +402,7 @@ elf_machine_rel (struct link_map *map, struct r_scope_elem *scope[], break; case R_ARM_ABS32: { - struct unaligned - { - Elf32_Addr x; - } __attribute__ ((packed, may_alias)); + ElfW(Addr) tmp; # ifndef RTLD_BOOTSTRAP /* This is defined in rtld.c, but nowhere in the static libc.a; make the reference weak so static programs can @@ -425,7 +422,9 @@ elf_machine_rel (struct link_map *map, struct r_scope_elem *scope[], value -= SYMBOL_ADDRESS (map, refsym, true); # endif /* Support relocations on mis-aligned offsets. */ - ((struct unaligned *) reloc_addr)->x += value; + memcpy(&tmp, reloc_addr, sizeof tmp); + tmp += value; + memcpy (reloc_addr, &tmp, sizeof tmp); break; } case R_ARM_TLS_DESC:
This recently came up during a cleanup to remove misaligned accesses from the RISC-V port. Link: https://sourceware.org/pipermail/libc-alpha/2022-June/139961.html Suggested-by: Adhemerval Zanella <adhemerval.zanella@linaro.org> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com> -- I haven't build this one, as I'm just doing it locally and don't have everything setup here. --- sysdeps/arm/dl-machine.h | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-)