1 files changed, 40 insertions, 5 deletions
diff --git a/arch/arm/boot/compressed/string.c b/arch/arm/boot/compressed/string.c
index 36e53ef9200f..fcc678fce045 100644
--- a/arch/arm/boot/compressed/string.c
+++ b/arch/arm/boot/compressed/string.c
@@ -1,11 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0
 /*
  * arch/arm/boot/compressed/string.c
  *
  * Small subset of simple string routines
  */
 
+#define __NO_FORTIFY
 #include <linux/string.h>
 
+/*
+ * The decompressor is built without KASan but uses the same redirects as the
+ * rest of the kernel when CONFIG_KASAN is enabled, defining e.g. memcpy()
+ * to __memcpy() but since we are not linking with the main kernel string
+ * library in the decompressor, that will lead to link failures.
+ *
+ * Undefine KASan's versions, define the wrapped functions and alias them to
+ * the right names so that when e.g. __memcpy() appear in the code, it will
+ * still be linked to this local version of memcpy().
+ */
+#ifdef CONFIG_KASAN
+#undef memcpy
+#undef memmove
+#undef memset
+void *__memcpy(void *__dest, __const void *__src, size_t __n) __alias(memcpy);
+void *__memmove(void *__dest, __const void *__src, size_t count) __alias(memmove);
+void *__memset(void *s, int c, size_t count) __alias(memset);
+#endif
+
 void *memcpy(void *__dest, __const void *__src, size_t __n)
 {
 	int i = 0;
@@ -65,6 +86,15 @@ size_t strlen(const char *s)
 	return sc - s;
 }
 
+size_t strnlen(const char *s, size_t count)
+{
+	const char *sc;
+
+	for (sc = s; count-- && *sc != '\0'; ++sc)
+		/* nothing */;
+	return sc - s;
+}
+
 int memcmp(const void *cs, const void *ct, size_t count)
 {
 	const unsigned char *su1 = cs, *su2 = ct, *end = su1 + count;
@@ -111,6 +141,16 @@ char *strchr(const char *s, int c)
 	return (char *)s;
 }
 
+char *strrchr(const char *s, int c)
+{
+	const char *last = NULL;
+	do {
+		if (*s == (char)c)
+			last = s;
+	} while (*s++);
+	return (char *)last;
+}
+
 #undef memset
 
 void *memset(void *s, int c, size_t count)
@@ -120,8 +160,3 @@ void *memset(void *s, int c, size_t count)
 		*xs++ = c;
 	return s;
 }
-
-void __memzero(void *s, size_t count)
-{
-	memset(s, 0, count);
-}