Re: [syzbot] [intel-wired-lan?] UBSAN: shift-out-of-bounds in e100_eeprom_load

[Yalagada Pavan Kumar <pavankumaryalagada@gmail.com>]

#syz test: git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master

diff --git a/drivers/net/ethernet/intel/e100.c b/drivers/net/ethernet/intel/e100.c
index 29960762e64a..5165f1d3c98f 100644
--- a/drivers/net/ethernet/intel/e100.c
+++ b/drivers/net/ethernet/intel/e100.c
@@ -744,7 +744,14 @@ static __le16 e100_eeprom_read(struct nic *nic, u16 *addr_len, u16 addr)
 		 * complete address.  Use this to adjust addr_len. */
 		ctrl = ioread8(&nic->csr->eeprom_ctrl_lo);
 		if (!(ctrl & eedo) && i > 16) {
-			*addr_len -= (i - 16);
+			u16 len = i - 16;
+
+			if (len > *addr_len) {
+				*addr_len = 0;
+				break;
+			}
+
+			*addr_len -= len;
 			i = 17;
 		}
 
@@ -765,7 +772,15 @@ static int e100_eeprom_load(struct nic *nic)
 
 	/* Try reading with an 8-bit addr len to discover actual addr len */
 	e100_eeprom_read(nic, &addr_len, 0);
-	nic->eeprom_wc = 1 << addr_len;
+
+	if (!addr_len || addr_len > 8) {
+		netif_err(nic, probe, nic->netdev,
+			"Invalid EEPROM address length %u\n",
+			addr_len);
+		return -EIO;
+	}
+
+	nic->eeprom_wc = (u16)BIT(addr_len);
 
 	for (addr = 0; addr < nic->eeprom_wc; addr++) {
 		nic->eeprom[addr] = e100_eeprom_read(nic, &addr_len, addr);
@@ -791,7 +806,15 @@ static int e100_eeprom_save(struct nic *nic, u16 start, u16 count)
 
 	/* Try reading with an 8-bit addr len to discover actual addr len */
 	e100_eeprom_read(nic, &addr_len, 0);
-	nic->eeprom_wc = 1 << addr_len;
+
+	if (!addr_len || addr_len > 8) {
+		netif_err(nic, probe, nic->netdev,
+			"Invalid EEPROM address length %u\n",
+			addr_len);
+		return -EIO;
+	}
+
+	nic->eeprom_wc = (u16)BIT(addr_len);
 
 	if (start + count >= nic->eeprom_wc)
 		return -EINVAL;