| Message ID | 20200316122820.11032-1-yangx.jy@cn.fujitsu.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | modpost: Get proper section index by get_secindex() instead of st_shndx | expand |
On 2020/3/16 20:28, Xiao Yang wrote: > (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. 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 > ... > [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") > Fixes: 5545322c86d9 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name") > Signed-off-by: Xiao Yang<yangx.jy@cn.fujitsu.com> > --- > 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;
On Tue, Mar 17, 2020 at 10:05 AM Xiao Yang <yangx.jy@cn.fujitsu.com> 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@cn.fujitsu.com> > > --- > > 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
On 2020/3/18 17:49, Masahiro Yamada wrote: > On Tue, Mar 17, 2020 at 10:05 AM Xiao Yang<yangx.jy@cn.fujitsu.com> 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. > Hi Masahiro, Sure, it is OK to delete it. > >>> ... >>> [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") > Will replace it with your suggested commit. > >>> 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") > > Sorry for the wrong commit hash. Thanks a lot for your quick review. I will send v2 patch soon. Best Regards, Xiao Yang > > > >>> Signed-off-by: Xiao Yang<yangx.jy@cn.fujitsu.com> >>> --- >>> 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 > > > . >
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;
(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 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 ... [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") Fixes: 5545322c86d9 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name") Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com> --- scripts/mod/modpost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)