linux-kernel - [PATCH AUTOSEL 5.5 16/28] modpost: Get proper section index by get_secindex() instead of st

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Date:   Thu, 26 Mar 2020 19:23:45 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Xiao Yang <yangx.jy@...fujitsu.com>,
        Masahiro Yamada <masahiroy@...nel.org>,
        Sasha Levin <sashal@...nel.org>, linux-kbuild@...r.kernel.org
Subject: [PATCH AUTOSEL 5.5 16/28] modpost: Get proper section index by get_secindex() instead of st_shndx

From: Xiao Yang <yangx.jy@...fujitsu.com>

[ Upstream commit 4b8a5cfb5fd375cf4c7502a18f0096ed2881be27 ]

(uint16_t) st_shndx is limited to 65535(i.e. SHN_XINDEX) so sym_get_data() gets
wrong section index by st_shndx if requested symbol contains extended section
index that is more than 65535.  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.

Fixes: 56067812d5b0 ("kbuild: modversions: add infrastructure for emitting relative CRCs")
Fixes: e84f9fbbece1 ("modpost: refactor namespace_from_kstrtabns() to not hard-code section name")
Signed-off-by: Xiao Yang <yangx.jy@...fujitsu.com>
Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 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 6e892c93d104a..90aaf29c61a0f 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -307,7 +307,8 @@ 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;
-- 
2.20.1