nbd: Fix potential signed overflow issues

Signed-off-by: NMax Reitz <mreitz@redhat.com>
Message-Id: <1424887718-10800-11-git-send-email-mreitz@redhat.com>
Signed-off-by: NPaolo Bonzini <pbonzini@redhat.com>

include/block/nbd.h

@@ -54,8 +54,8 @@ struct nbd_reply {
 /* Reply types. */
 #define NBD_REP_ACK             (1)             /* Data sending finished. */
 #define NBD_REP_SERVER          (2)             /* Export description. */
-#define NBD_REP_ERR_UNSUP       ((1 << 31) | 1) /* Unknown option. */
-#define NBD_REP_ERR_INVALID     ((1 << 31) | 3) /* Invalid length. */
+#define NBD_REP_ERR_UNSUP       ((UINT32_C(1) << 31) | 1) /* Unknown option. */
+#define NBD_REP_ERR_INVALID     ((UINT32_C(1) << 31) | 3) /* Invalid length. */
 
 #define NBD_CMD_MASK_COMMAND	0x0000ffff
 #define NBD_CMD_FLAG_FUA	(1 << 16)

qemu-nbd.c

@@ -142,8 +142,9 @@ static void read_partition(uint8_t *p, struct partition_record *r)
     r->end_head = p[5];
     r->end_cylinder = p[7] | ((p[6] << 2) & 0x300);
     r->end_sector = p[6] & 0x3f;
-    r->start_sector_abs = p[8] | p[9] << 8 | p[10] << 16 | p[11] << 24;
-    r->nb_sectors_abs = p[12] | p[13] << 8 | p[14] << 16 | p[15] << 24;
+
+    r->start_sector_abs = le32_to_cpup((uint32_t *)(p +  8));
+    r->nb_sectors_abs   = le32_to_cpup((uint32_t *)(p + 12));
 }
 
 static int find_partition(BlockBackend *blk, int partition,