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, "$");
printf("test1: %d\n", is_arm_mapping_symbol(str1));
printf("test2: %d\n", is_arm_mapping_symbol(str2));
Result
------
test1: 0
test2: 1
Signed-off-by: Masahiro Yamada <masahiroy@xxxxxxxxxx>
---
scripts/mod/modpost.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 6f5c605ab0fb..845bc438ca49 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1179,7 +1179,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
static inline int is_arm_mapping_symbol(const char *str)
{
- return str[0] == '$' && 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
