From: Masahiro Yamada masahiroy@kernel.org
[ Upstream commit d6b732666a1bae0df3c3ae06925043bba34502b1 ]
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, "$");
printf("test1: %d\n", is_arm_mapping_symbol(str1)); printf("test2: %d\n", is_arm_mapping_symbol(str2));
Result ------
test1: 0 test2: 1
Signed-off-by: Masahiro Yamada masahiroy@kernel.org Reviewed-by: Nick Desaulniers ndesaulniers@google.com Signed-off-by: Sasha Levin sashal@kernel.org --- scripts/mod/modpost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index e08f75aed429..2d3c3962c229 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1271,7 +1271,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
static inline int is_arm_mapping_symbol(const char *str) { - return str[0] == '$' && strchr("axtd", str[1]) + return str[0] == '$' && + (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x') && (str[2] == '\0' || str[2] == '.'); }