diff -up util-linux-2.23.2/libblkid/src/partitions/dos.c.kzak util-linux-2.23.2/libblkid/src/partitions/dos.c

--- util-linux-2.23.2/libblkid/src/partitions/dos.c.kzak	2015-08-21 10:16:45.244332027 +0200

+++ util-linux-2.23.2/libblkid/src/partitions/dos.c	2015-08-21 10:22:07.181340367 +0200

@@ -151,16 +151,6 @@ static int probe_dos_pt(blkid_probe pr,

 	if (memcmp(data, BLKID_AIX_MAGIC_STRING, BLKID_AIX_MAGIC_STRLEN) == 0)

 		goto nothing;

-	/*

-	 * Now that the 55aa signature is present, this is probably

-	 * either the boot sector of a FAT filesystem or a DOS-type

-	 * partition table.

-	 */

-	if (blkid_probe_is_vfat(pr) == 1) {

-		DBG(LOWPROBE, blkid_debug("probably FAT -- ignore"));

-		goto nothing;

-	}

-

 	p0 = (struct dos_partition *) (data + BLKID_MSDOS_PT_OFFSET);

 	/*

@@ -182,6 +172,16 @@ static int probe_dos_pt(blkid_probe pr,

 		}

 	}

+	/*

+	 * Now that the 55aa signature is present, this is probably

+	 * either the boot sector of a FAT filesystem or a DOS-type

+	 * partition table.

+	 */

+	if (blkid_probe_is_vfat(pr) == 1) {

+		DBG(LOWPROBE, blkid_debug("probably FAT -- ignore"));

+		goto nothing;

+	}

+

 	blkid_probe_use_wiper(pr, BLKID_MSDOS_PT_OFFSET,

 				  512 - BLKID_MSDOS_PT_OFFSET);

diff -up util-linux-2.23.2/libblkid/src/partitions/dos.h.kzak util-linux-2.23.2/libblkid/src/partitions/dos.h

--- util-linux-2.23.2/libblkid/src/partitions/dos.h.kzak	2015-08-21 10:34:14.919380422 +0200

+++ util-linux-2.23.2/libblkid/src/partitions/dos.h	2015-08-21 10:35:45.221807669 +0200

@@ -12,6 +12,12 @@ struct dos_partition {

 #define BLKID_MSDOS_PT_OFFSET		0x1be

+static inline struct dos_partition *mbr_get_partition(unsigned char *mbr, int i)

+{

+	return (struct dos_partition *)

+		(mbr + BLKID_MSDOS_PT_OFFSET + (i * sizeof(struct dos_partition)));

+}

+

 /* assemble badly aligned little endian integer */

 static inline unsigned int assemble4le(const unsigned char *p)

 {

diff -up util-linux-2.23.2/libblkid/src/superblocks/vfat.c.kzak util-linux-2.23.2/libblkid/src/superblocks/vfat.c

--- util-linux-2.23.2/libblkid/src/superblocks/vfat.c.kzak	2015-08-21 10:10:12.111906711 +0200

+++ util-linux-2.23.2/libblkid/src/superblocks/vfat.c	2015-08-21 10:35:07.733045452 +0200

@@ -16,6 +16,7 @@

 #include <ctype.h>

 #include <stdint.h>

+#include "partitions/dos.h"

 #include "superblocks.h"

 /* Yucky misaligned values */

@@ -169,7 +170,8 @@ static unsigned char *search_fat_label(b

 	return NULL;

 }

-static int fat_valid_superblock(const struct blkid_idmag *mag,

+static int fat_valid_superblock(blkid_probe pr,

+			const struct blkid_idmag *mag,

 			struct msdos_super_block *ms,

 			struct vfat_super_block *vs,

 			uint32_t *cluster_count, uint32_t *fat_size)

@@ -243,6 +245,20 @@ static int fat_valid_superblock(const st

 	if (cluster_count)

 		*cluster_count = __cluster_count;

+	if (blkid_probe_is_wholedisk(pr)) {

+		/* OK, seems like FAT, but it's possible that we found boot

+		 * sector with crazy FAT-like stuff (magic strings, media,

+		 * etc..) before MBR. Let's make sure that there is no MBR with

+		 * usable partition. */

+		unsigned char *buf = (unsigned char *) ms;

+		if (is_valid_mbr_signature(buf)) {

+			struct dos_partition *p0 = mbr_get_partition(buf, 0);

+			if (dos_partition_size(p0) != 0 &&

+			    (p0->boot_ind == 0 || p0->boot_ind == 0x80))

+				return 0;

+		}

+	}

+

 	return 1;	/* valid */

 }

@@ -270,7 +286,7 @@ int blkid_probe_is_vfat(blkid_probe pr)

 	if (!vs)

 		return errno ? -errno : 0;

-	return fat_valid_superblock(mag, ms, vs, NULL, NULL);

+	return fat_valid_superblock(pr, mag, ms, vs, NULL, NULL);

 }

 /* FAT label extraction from the root directory taken from Kay

@@ -293,7 +309,7 @@ static int probe_vfat(blkid_probe pr, co

 	if (!vs)

 		return errno ? -errno : 1;

-	if (!fat_valid_superblock(mag, ms, vs, &cluster_count, &fat_size))

+	if (!fat_valid_superblock(pr, mag, ms, vs, &cluster_count, &fat_size))

 		return 1;

 	sector_size = unaligned_le16(&ms->ms_sector_size);