net: s2io: fix buffer overflow

vpd_data[] is allocated as kmalloc(256, GFP_KERNEL), so if cnt = 255
then (cnt + 3) overflows 256. memset() is executed without checking.
vpd_data[cnt+2] must be less than 256-cnt-2 as the latter is number of
vpd_data[] elements to copy.

Do not fill with zero the beginning of nic->serial_num as it will
be filled with vpd_data[].

String in product_name[] should be terminated by '\0'.

Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/s2io.c b/drivers/net/s2io.c
index b8b8584..18bc5b7 100644 (file)
--- a/drivers/net/s2io.c
+++ b/drivers/net/s2io.c
@@ -5796,7 +5796,7 @@ static void s2io_vpd_read(struct s2io_nic *nic)
 {
        u8 *vpd_data;
        u8 data;
-       int i = 0, cnt, fail = 0;
+       int i = 0, cnt, len, fail = 0;
        int vpd_addr = 0x80;
        struct swStat *swstats = &nic->mac_control.stats_info->sw_stat;
 
@@ -5837,20 +5837,28 @@ static void s2io_vpd_read(struct s2io_nic *nic)
 
        if (!fail) {
                /* read serial number of adapter */
-               for (cnt = 0; cnt < 256; cnt++) {
+               for (cnt = 0; cnt < 252; cnt++) {
                        if ((vpd_data[cnt] == 'S') &&
-                           (vpd_data[cnt+1] == 'N') &&
-                           (vpd_data[cnt+2] < VPD_STRING_LEN)) {
-                               memset(nic->serial_num, 0, VPD_STRING_LEN);
-                               memcpy(nic->serial_num, &vpd_data[cnt + 3],
-                                      vpd_data[cnt+2]);
-                               break;
+                           (vpd_data[cnt+1] == 'N')) {
+                               len = vpd_data[cnt+2];
+                               if (len < min(VPD_STRING_LEN, 256-cnt-2)) {
+                                       memcpy(nic->serial_num,
+                                              &vpd_data[cnt + 3],
+                                              len);
+                                       memset(nic->serial_num+len,
+                                              0,
+                                              VPD_STRING_LEN-len);
+                                       break;
+                               }
                        }
                }
        }
 
-       if ((!fail) && (vpd_data[1] < VPD_STRING_LEN))
-               memcpy(nic->product_name, &vpd_data[3], vpd_data[1]);
+       if ((!fail) && (vpd_data[1] < VPD_STRING_LEN)) {
+               len = vpd_data[1];
+               memcpy(nic->product_name, &vpd_data[3], len);
+               nic->product_name[len] = 0;
+       }
        kfree(vpd_data);
        swstats->mem_freed += 256;
 }