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authorMasahiro Yamada <masahiroy@kernel.org>2022-05-23 19:46:22 +0300
committerMasahiro Yamada <masahiroy@kernel.org>2022-05-27 10:07:44 +0300
commitd6b732666a1bae0df3c3ae06925043bba34502b1 (patch)
treee9fad3eb40a8b359ddb489843baf410793310749 /scripts/mod
parentb5beffa20d83c4e15306c991ffd00de0d8628338 (diff)
downloadlinux-d6b732666a1bae0df3c3ae06925043bba34502b1.tar.xz
modpost: fix undefined behavior of is_arm_mapping_symbol()
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, "$"); printf("test1: %d\n", is_arm_mapping_symbol(str1)); printf("test2: %d\n", is_arm_mapping_symbol(str2)); Result ------ test1: 0 test2: 1 Signed-off-by: Masahiro Yamada <masahiroy@kernel.org> Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Diffstat (limited to 'scripts/mod')
-rw-r--r--scripts/mod/modpost.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/scripts/mod/modpost.c b/scripts/mod/modpost.c
index 08f6989437bd..1092906867f0 100644
--- a/scripts/mod/modpost.c
+++ b/scripts/mod/modpost.c
@@ -1180,7 +1180,8 @@ static int secref_whitelist(const struct sectioncheck *mismatch,
static inline int is_arm_mapping_symbol(const char *str)
{
- return str[0] == '$' && strchr("axtd", str[1])
+ return str[0] == '$' &&
+ (str[1] == 'a' || str[1] == 'd' || str[1] == 't' || str[1] == 'x')
&& (str[2] == '\0' || str[2] == '.');
}