Messages in this thread Patch in this message | | | From | Sasha Levin <> | Subject | [PATCH AUTOSEL 5.4 27/34] modpost: fix undefined behavior of is_arm_mapping_symbol() | Date | Tue, 7 Jun 2022 14:00:02 -0400 |
| |
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, "$");
printf("test1: %d\n", is_arm_mapping_symbol(str1)); printf("test2: %d\n", is_arm_mapping_symbol(str2));
Result ------
test1: 0 test2: 1
Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Sasha Levin <sashal@kernel.org> --- scripts/mod/modpost.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c index 13cda6aa2688..a878c79fe95a 100644 --- a/scripts/mod/modpost.c +++ b/scripts/mod/modpost.c @@ -1283,7 +1283,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch, static inline int is_arm_mapping_symbol(const char *str) { - return str[0] == '$' && strchr("axtd", str[1]) + return str[0] == '$' && + (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x') && (str[2] == '\0' || str[2] == '.'); } -- 2.35.1
| |