linux-kernel - [PATCH] module: fix validate_section

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Date:   Fri, 15 Oct 2021 14:57:41 -0600
From:   Shuah Khan <skhan@...uxfoundation.org>
To:     mcgrof@...nel.org, jeyu@...nel.org
Cc:     Shuah Khan <skhan@...uxfoundation.org>,
        linux-kernel@...r.kernel.org
Subject: [PATCH] module: fix validate_section_offset() overflow bug on 64-bit

validate_section_offset() uses unsigned long local variable to
add/store shdr->sh_offset and shdr->sh_size on all platforms.
unsigned long is too short when sh_offset is Elf64_Off which
would be the case on 64bit ELF headers.

Fix the overflow problem using the right size local variable when
CONFIG_64BIT is defined.

Signed-off-by: Shuah Khan <skhan@...uxfoundation.org>
---
 kernel/module.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/kernel/module.c b/kernel/module.c
index f5d6e388478c..e7402fb1f4e7 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -2942,7 +2942,11 @@ static int module_sig_check(struct load_info *info, int flags)
 
 static int validate_section_offset(struct load_info *info, Elf_Shdr *shdr)
 {
+#if defined(CONFIG_64BIT)
+	unsigned long long secend;
+#else
 	unsigned long secend;
+#endif
 
 	/*
 	 * Check for both overflow and offset/size being
-- 
2.30.2