On Tue, Mar 17, 2020 at 10:05 AM Xiao Yang <yangx.jy@xxxxxxxxxxxxxx> wrote:
>
> On 2020/3/16 20:28, Xiao Yang wrote:
Thanks for catching this bug.
> > (uint16_t) st_shndx is limited to 65535(i.e. SHN_XINDEX) so sym_get_data() gets
> > wrong section index by st_shndx if object file(e.g. vmlinux.o) has more than
> Hi,
>
> It seems better to say that sym_get_data() gets wrong section index by
> st_shndx if requested symbol contains extended section index that is
> more than 65535.
Sounds good to me.
> Thanks,
> Xiao Yang
> > 65535 sessions. In this case, we need to get proper section index by .symtab_shndx
> > section.
> >
> > Module.symvers generated by building kernel with "-ffunction-sections -fdata-sections"
> > shows the issue(i.e. cannot get 89902 by st_shndx):
> > -------------------------------------------------------------------
> > [root@Fedora-30 linux]# file Module.symvers
> > Module.symvers: data
> > [root@Fedora-30 linux]# head -n1 Module.symvers
> > 0x5caf3011 ipv6_chk_custom_prefix ▒▒▒▒▒▒▒▒ vmlinux EXPORT_SYMBOL
Could you delete this dump?
I'd like to avoid garbling where possible.
> > ...
> > [root@Fedora-30 linux]# readelf -s -W vmlinux.o | grep __kstrtabns_ipv6_chk_custom_prefix
> > 199174: 0000000000032578 1 OBJECT LOCAL DEFAULT 89902 __kstrtabns_ipv6_chk_custom_prefix
> > [root@Fedora-30 linux]# readelf -S -W vmlinux.o | grep 89902
> > [89902] __ksymtab_strings PROGBITS 0000000000000000 a94e00 0345a2 00 A 0 0 1
> > -------------------------------------------------------------------
> >
> > Fixes: afa0459daa7b ("modpost: add a helper to get data pointed by a symbol")
Strictly speaking, this commit does not introduce any bug.
The CRC bug for MODVERSIONS exists since
56067812d5b0 ("kbuild: modversions: add infrastructure for emitting
relative CRCs")
> > Fixes: 5545322c86d9 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name")
This commit hash is wrong.
The correct one is
Fixes: e84f9fbbece1 ("modpost: refactor namespace_from_kstrtabns() to
not hard-code section name")
> > Signed-off-by: Xiao Yang<yangx.jy@xxxxxxxxxxxxxx>
> > ---
> > scripts/mod/modpost.c | 3 ++-
> > 1 file changed, 2 insertions(+), 1 deletion(-)
> >
> > diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
> > index d9418c58a8c0..c1fec8cac257 100644
> > --- a/scripts/mod/modpost.c
> > +++ b/scripts/mod/modpost.c
> > @@ -310,7 +310,8 @@ static const char *sec_name(struct elf_info *elf, int secindex)
> >
> > static void *sym_get_data(const struct elf_info *info, const Elf_Sym *sym)
> > {
> > - Elf_Shdr *sechdr =&info->sechdrs[sym->st_shndx];
> > + unsigned int secindex = get_secindex(info, sym);
> > + Elf_Shdr *sechdr =&info->sechdrs[secindex];
> > unsigned long offset;
> >
> > offset = sym->st_value;
>
>
>
--
Best Regards
Masahiro Yamada
