kernel: add ubsan bindings, fix some UB reported by it

kernel-src/io/pci.c

@@ -12,6 +12,11 @@ uint16_t pci_read16(int bus, int device, int function, uint32_t offset) {
 	return (pci_archread32(bus, device, function, offset) >> ((offset & 0b11) * 8)) & 0xffff;
 }
 
+uint32_t pci_read32(int bus, int device, int function, uint32_t offset) {
+	return pci_archread32(bus, device, function, offset);
+}
+
+
 void pci_write8(int bus, int device, int function, uint32_t offset, uint8_t v) {
 	uint32_t old = pci_archread32(bus, device, function, offset);
 	int bitoffset = 8 * (offset & 0b11);
@@ -23,19 +28,16 @@ void pci_write8(int bus, int device, int function, uint32_t offset, uint8_t v) {
 void pci_write16(int bus, int device, int function, uint32_t offset, uint16_t v) {
 	uint32_t old = pci_archread32(bus, device, function, offset);
 	int bitoffset = 8 * (offset & 0b11);
-	old &= ~(0xffff << bitoffset);
-	old |= v << bitoffset;
+	old &= ~(0xfffflu << bitoffset);
+	old |= (uint32_t)v << bitoffset;
 	pci_archwrite32(bus, device, function, offset, old);
 }
 
-uint32_t pci_read32(int bus, int device, int function, uint32_t offset) {
-	return pci_archread32(bus, device, function, offset);
-}
-
 void pci_write32(int bus, int device, int function, uint32_t offset, uint32_t value) {
 	pci_archwrite32(bus, device, function, offset, value);
 }
 
+
 int pci_getcapoffset(pcienum_t *e, int cap, int n) {
 	if ((PCI_READ16(e, PCI_CONFIG_STATUS) & PCI_STATUS_HASCAP) == 0)
 		return 0;

kernel-src/io/pseudodevices.c

@@ -30,7 +30,7 @@ static int maxseek(int minor, size_t *max) {
 
 static long current = 0xdeadbeefbadc0ffe;
 
-static uint8_t getrand8() {
+__attribute__((no_sanitize("undefined"))) static uint8_t getrand8() {
 	current += timekeeper_timefromboot().ns * timekeeper_timefromboot().s - timekeeper_time().ns * timekeeper_time().s + timekeeper_time().s;
 	return current & 0xff;
 }