Avoid shift overflow in memmem(3) and strstr(3)

Fix from upstream musl:
https://git.musl-libc.org/cgit/musl/commit?id=593caa456309714402ca4cb77c3770f4c24da9da

OK tb@

1 files changed, 5 insertions, 5 deletions

diff --git a/src/lib/libc/string/memmem.c b/src/lib/libc/string/memmem.c
index 3b180b4a62..e87c7be37a 100644
--- a/src/lib/libc/string/memmem.c
+++ b/src/lib/libc/string/memmem.c
@@ -1,4 +1,4 @@
-/*      $OpenBSD: memmem.c,v 1.5 2020/04/16 12:39:28 claudio Exp $ */
+/*      $OpenBSD: memmem.c,v 1.6 2026/06/23 13:09:11 tim Exp $ */
 
 /*
  * Copyright (c) 2005-2020 Rich Felker, et al.
@@ -38,8 +38,8 @@ twobyte_memmem(const unsigned char *h, size_t k, const unsigned char *n)
 static char *
 threebyte_memmem(const unsigned char *h, size_t k, 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+=3, k-=3; k; k--, hw = (hw|*h++)<<8)
                 if (hw == nw) return (char *)h-3;
         return hw == nw ? (char *)h-3 : 0;
@@ -48,8 +48,8 @@ threebyte_memmem(const unsigned char *h, size_t k, const unsigned char *n)
 static char *
 fourbyte_memmem(const unsigned char *h, size_t k, 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+=4, k-=4; k; k--, hw = hw<<8 | *h++)
                 if (hw == nw) return (char *)h-4;
         return hw == nw ? (char *)h-4 : 0;