diff options
| author | Mark Wielaard <mark@klomp.org> | 2020-08-19 23:41:24 +0200 |
|---|---|---|
| committer | Mark Wielaard <mark@klomp.org> | 2020-08-19 23:47:40 +0200 |
| commit | 55c5c9a568ed707bcea1388bf3a525212d8cf4b8 (patch) | |
| tree | 68be81a4525baf3477099a083d7dd1821403c5bb /libelf | |
| parent | 15495182302edbe0142101ec3a09e478901ab994 (diff) | |
| download | elfutils-55c5c9a568ed707bcea1388bf3a525212d8cf4b8.tar.gz | |
libelf: Fixup SHF_COMPRESSED sh_addralign in elf_update if necessary.
In elf_getdata.c we have the following to compensate for possibly
bad sh_addralign values of compressed sections:
/* Compressed data has a header, but then compressed data.
Make sure to set the alignment of the header explicitly,
don't trust the file alignment for the section, it is
often wrong. */
if ((flags & SHF_COMPRESSED) != 0)
{
entsize = 1;
align = __libelf_type_align (elf->class, ELF_T_CHDR);
}
Which makes sure the d_data alignment is correct for the Chdr struct
at the start of the compressed section.
But this means that if a user just reads such a compressed section
without changing it, and then tries to write it out again using
elf_update they get an error message about d_align and sh_addralign
being out of sync.
We already correct obviously incorrect sh_entsize fields.
Do the same for the sh_addralign field of a SHF_COMPRESSED section.
Signed-off-by: Mark Wielaard <mark@klomp.org>
Diffstat (limited to 'libelf')
| -rw-r--r-- | libelf/ChangeLog | 5 | ||||
| -rw-r--r-- | libelf/elf32_updatenull.c | 12 |
2 files changed, 17 insertions, 0 deletions
diff --git a/libelf/ChangeLog b/libelf/ChangeLog index 8f6d2d2d..77044c1c 100644 --- a/libelf/ChangeLog +++ b/libelf/ChangeLog @@ -1,3 +1,8 @@ +2020-08-19 Mark Wielaard <mark@klomp.org> + + * elf32_updatenull.c (updatenull_wrlock): Fixup the sh_addralign + of an SHF_COMPRESSED section if necessary. + 2020-06-04 Mark Wielaard <mark@klomp.org> * elf.h: Update from glibc. diff --git a/libelf/elf32_updatenull.c b/libelf/elf32_updatenull.c index 5f3cdbf6..d0d4d1eb 100644 --- a/libelf/elf32_updatenull.c +++ b/libelf/elf32_updatenull.c @@ -267,6 +267,18 @@ __elfw2(LIBELFBITS,updatenull_wrlock) (Elf *elf, int *change_bop, size_t shnum) update_if_changed (shdr->sh_entsize, sh_entsize, scn->shdr_flags); + /* Likewise for the alignment of a compressed section. + For a SHF_COMPRESSED section set the correct + sh_addralign value, which must match the d_align of + the data (see __libelf_set_rawdata in elf_getdata.c). */ + if ((shdr->sh_flags & SHF_COMPRESSED) != 0) + { + sh_align = __libelf_type_align (ELFW(ELFCLASS,LIBELFBITS), + ELF_T_CHDR); + update_if_changed (shdr->sh_addralign, sh_align, + scn->shdr_flags); + } + if (scn->data_read == 0 && __libelf_set_rawdata_wrlock (scn) != 0) /* Something went wrong. The error value is already set. */ |