fix undefined behavior from signed overflow in strstr and memmem

[musl] / src / string / strstr.c

diff --git a/src/string/strstr.c b/src/string/strstr.c
index 55ba1c7..43a0207 100644 (file)
--- a/src/string/strstr.c
+++ b/src/string/strstr.c
@@ -10,16 +10,16 @@ static char *twobyte_strstr(const unsigned char *h, const unsigned char *n)
 
 static char *threebyte_strstr(const unsigned char *h, const unsigned char *n)
 {
-       uint32_t nw = n[0]<<24 | n[1]<<16 | n[2]<<8;
-       uint32_t hw = h[0]<<24 | h[1]<<16 | h[2]<<8;
+       uint32_t nw = (uint32_t)n[0]<<24 | n[1]<<16 | n[2]<<8;
+       uint32_t hw = (uint32_t)h[0]<<24 | h[1]<<16 | h[2]<<8;
        for (h+=2; *h && hw != nw; hw = (hw|*++h)<<8);
        return *h ? (char *)h-2 : 0;
 }
 
 static char *fourbyte_strstr(const unsigned char *h, const unsigned char *n)
 {
-       uint32_t nw = n[0]<<24 | n[1]<<16 | n[2]<<8 | n[3];
-       uint32_t hw = h[0]<<24 | h[1]<<16 | h[2]<<8 | h[3];
+       uint32_t nw = (uint32_t)n[0]<<24 | n[1]<<16 | n[2]<<8 | n[3];
+       uint32_t hw = (uint32_t)h[0]<<24 | h[1]<<16 | h[2]<<8 | h[3];
        for (h+=3; *h && hw != nw; hw = hw<<8 | *++h);
        return *h ? (char *)h-3 : 0;
 }