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@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;
