Fixed an extremely rare crash on 10.12.

Changelog.md

@@ -23,6 +23,7 @@ AppleALC Changelog
 - Added ALC887 layout-id 33 for GA-Q87TN by klblk
 - Added ALC256 (3246) codec support layout-id 13 by InsanelyDeepak
 - Added ALC255 layout-id 13 and 17 by InsanelyDeepak
+- Fixed an extremely rare crash on 10.12
 
 #### v1.0.16
 - Fixed a rare lock acquisition issue on 10.12

Common/kern_patcher.cpp

@@ -214,27 +214,30 @@ void KernelPatcher::applyLookupPatch(const LookupPatch *patch) {
 	curr = off;
 	off += size - patch->size;
 	size_t changes {0};
+
+	if (kinfo->setKernelWriting(true) != KERN_SUCCESS) {
+		SYSLOG("patcher @ lookup patching failed to write to kernel");
+		code = Error::MemoryProtection;
+		return;
+	}
+
 	for (size_t i = 0; curr < off && (i < patch->count || patch->count == 0); i++) {
 		while (curr < off && memcmp(curr, patch->find, patch->size))
 			curr++;
 
 		if (curr != off) {
-			if (kinfo->setKernelWriting(true) != KERN_SUCCESS) {
-				SYSLOG("patcher @ lookup patching failed to write to kernel");
-				code = Error::MemoryProtection;
-				return;
-			}
 			for (size_t j = 0; j < patch->size; j++) {
 				curr[j] = patch->replace[j];
 			}
-			if (kinfo->setKernelWriting(false) != KERN_SUCCESS) {
-				SYSLOG("patcher @ lookup patching failed to disable kernel writing");
-				code = Error::MemoryProtection;
-				return;
-			}
 			changes++;
 		}
 	}
+
+	if (kinfo->setKernelWriting(false) != KERN_SUCCESS) {
+		SYSLOG("patcher @ lookup patching failed to disable kernel writing");
+		code = Error::MemoryProtection;
+		return;
+	}
 
 	if (changes != patch->count) {
 		SYSLOG("patcher @ lookup patching applied only %zu patches out of %zu", changes, patch->count);
@@ -424,4 +427,4 @@ void KernelPatcher::onKextSummariesUpdated() {
 		}
 	}
 }
-#endif /* KEXTPATCH_SUPPORT */
+#endif /* KEXTPATCH_SUPPORT */