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* [PATCH 1/5] modpost: fix undefined behavior of is_arm_mapping_symbol()
@ 2022-05-23 16:46 Masahiro Yamada
  2022-05-23 16:46 ` [PATCH 2/5] modpost: remove the unused argument of check_sec_ref() Masahiro Yamada
                   ` (4 more replies)
  0 siblings, 5 replies; 11+ messages in thread
From: Masahiro Yamada @ 2022-05-23 16:46 UTC (permalink / raw)
  To: linux-kbuild
  Cc: linux-kernel, Masahiro Yamada, Michal Marek, Nick Desaulniers

The return value of is_arm_mapping_symbol() is unpredictable when
"$" is passed in.

strchr(3) says:
  The strchr() and strrchr() functions return a pointer to the matched
  character or NULL if the character is not found. The terminating null
  byte is considered part of the string, so that if c is specified as
  '\0', these functions return a pointer to the terminator.

When str[1] is '\0', strchr("axtd", str[1]) is not NULL, and str[2] is
referenced (i.e. buffer overrun).

Test code
---------

  char str1[] = "abc";
  char str2[] = "ab";

  strcpy(str1, "$");
  strcpy(str2, "$");

  printf("test1: %d\n", is_arm_mapping_symbol(str1));
  printf("test2: %d\n", is_arm_mapping_symbol(str2));

Result
------

  test1: 0
  test2: 1

Signed-off-by: Masahiro Yamada <masahiroy@kernel.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 6f5c605ab0fb..845bc438ca49 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1179,7 +1179,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
 
 static inline int is_arm_mapping_symbol(const char *str)
 {
-	return str[0] == '$' && strchr("axtd", str[1])
+	return str[0] == '$' &&
+	       (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x')
 	       && (str[2] == '\0' || str[2] == '.');
 }
 
-- 
2.32.0


^ permalink raw reply related	[flat|nested] 11+ messages in thread
end of thread, other threads:[~2022-05-26 10:49 UTC | newest]

Thread overview: 11+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2022-05-23 16:46 [PATCH 1/5] modpost: fix undefined behavior of is_arm_mapping_symbol() Masahiro Yamada
2022-05-23 16:46 ` [PATCH 2/5] modpost: remove the unused argument of check_sec_ref() Masahiro Yamada
2022-05-24 20:44   ` Nick Desaulniers
2022-05-26 10:47     ` Masahiro Yamada
2022-05-23 16:46 ` [PATCH 3/5] modpost: simplify mod->name allocation Masahiro Yamada
2022-05-24 20:47   ` Nick Desaulniers
2022-05-23 16:46 ` [PATCH 4/5] modpost: reuse ARRAY_SIZE() macro for section_mismatch() Masahiro Yamada
2022-05-24 20:49   ` Nick Desaulniers
2022-05-23 16:46 ` [PATCH 5/5] modpost: squash if...else if in find_elf_symbol2() Masahiro Yamada
2022-05-24 20:51   ` Nick Desaulniers
2022-05-24 20:42 ` [PATCH 1/5] modpost: fix undefined behavior of is_arm_mapping_symbol() Nick Desaulniers

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