purecap-kasan: Save some KASAN_MALLOC_REDZONE bits

We still need some KASAN_MALLOC_REDZONE bits to cover inexact bounds. This is hopefully a temporary measure, but for sanitisation, we need it.
RoundofThree · Nov 19, 2024 · cfce178 · cfce178
1 parent 711b1e3
commit cfce178
Showing 1 changed file with 23 additions and 13 deletions.
diff --git a/sys/kern/kern_malloc.c b/sys/kern/kern_malloc.c
@@ -702,16 +702,18 @@ void *
 	if (va != NULL)
 		va = redzone_setup(va, osize);
 #endif
-#ifdef KASAN
+#if defined(KASAN) && !defined(__CHERI_PURE_CAPABILITY__)
 	if (va != NULL)
 		kasan_mark((void *)va, osize, size, KASAN_MALLOC_REDZONE);
 #endif
 #ifdef __CHERI_PURE_CAPABILITY__
-	va = cheri_setbounds(va, osize);
-	KASSERT(cheri_getlen(va) <= CHERI_REPRESENTABLE_LENGTH(osize),
-	    ("Invalid bounds: expected %zx found %zx",
-	        (size_t)CHERI_REPRESENTABLE_LENGTH(osize),
-	        (size_t)cheri_getlen(va)));
+	if (va != NULL) {
+		va = cheri_setbounds(va, osize);
+		if (osize < CHERI_REPRESENTABLE_LENGTH(osize)) {
+			kasan_mark((void *)va, osize, CHERI_REPRESENTABLE_LENGTH(osize),
+				KASAN_MALLOC_REDZONE);
+		}
+	}
 #endif
 	return ((void *) va);
 }
@@ -780,7 +782,7 @@ malloc_domainset(size_t size, struct malloc_type *mtp, struct domainset *ds,
 	if (va != NULL)
 		va = redzone_setup(va, osize);
 #endif
-#ifdef KASAN
+#if defined(KASAN) && !defined(__CHERI_PURE_CAPABILITY__)
 	if (va != NULL)
 		kasan_mark((void *)va, osize, size, KASAN_MALLOC_REDZONE);
 #endif
@@ -791,11 +793,12 @@ malloc_domainset(size_t size, struct malloc_type *mtp, struct domainset *ds,
 	}
 #endif
 #ifdef __CHERI_PURE_CAPABILITY__
-	va = cheri_setbounds(va, osize);
-	KASSERT(cheri_getlen(va) <= CHERI_REPRESENTABLE_LENGTH(osize),
-	    ("Invalid bounds: expected %zx found %zx",
-	        (size_t)CHERI_REPRESENTABLE_LENGTH(osize),
-	        (size_t)cheri_getlen(va)));
+	if (va != NULL) {
+		va = cheri_setbounds(va, osize);
+		if (osize < CHERI_REPRESENTABLE_LENGTH(osize)) {
+			kasan_mark((void *)va, osize, CHERI_REPRESENTABLE_LENGTH(osize), KASAN_MALLOC_REDZONE);
+		}
+	}
 #endif
 	return (va);
 }
@@ -1158,7 +1161,14 @@ realloc(void *addr, size_t size, struct malloc_type *mtp, int flags)
 	/* Reuse the original block if appropriate */
 	if (size <= alloc &&
 	    (size > (alloc >> REALLOC_FRACTION) || alloc == MINALLOCSIZE)) {
-		kasan_mark((void *)addr, size, alloc, KASAN_MALLOC_REDZONE);
+		if (!malloc_large_slab(slab)) {
+			if (size < CHERI_REPRESENTABLE_LENGTH(size)) {
+				kasan_mark((void *)addr, size, CHERI_REPRESENTABLE_LENGTH(size),
+					KASAN_MALLOC_REDZONE);
+			}
+		} else {
+			kasan_mark((void *)addr, size, alloc, KASAN_MALLOC_REDZONE);
+		}
 		return (addr);
 	}
 #endif /* !DEBUG_REDZONE */