fdisk: gpt: check header size

index 4a535f2..df26696 100644
@@ -49,6 +49,7 @@
 #define GPT_HEADER_REVISION_V1_02 0x00010200
 #define GPT_HEADER_REVISION_V1_00 0x00010000
 #define GPT_HEADER_REVISION_V0_99 0x00009900
+#define GPT_HEADER_MINSZ          92 /* bytes */
 
 #define GPT_PMBR_LBA        0
 #define GPT_MBR_PROTECTIVE  1

@@ -183,7 +184,7 @@ static struct fdisk_parttype gpt_parttypes[] =
 	DEF_GUID("E6D6D379-F507-44C2-A23C-238F2A3DF928", N_("Linux LVM")),
 	DEF_GUID("8DA63339-0007-60C0-C436-083AC8230908", N_("Linux reserved")),
 
-      /* FreeBSD */
+	/* FreeBSD */
 	DEF_GUID("516E7CB4-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD data")),
 	DEF_GUID("83BD6B9D-7F41-11DC-BE0B-001560B84F0F", N_("FreeBSD boot")),
 	DEF_GUID("516E7CB5-6ECF-11D6-8FF8-00022D09712B", N_("FreeBSD swap")),

@@ -660,6 +661,7 @@ static int gpt_check_signature(struct gpt_header *header)
 static struct gpt_header *gpt_get_header(struct fdisk_context *cxt, uint64_t lba)
 {
 	struct gpt_header *header = NULL;
+	uint32_t hsz;
 
 	if (!cxt)
 		return NULL;

@@ -684,6 +686,11 @@ static struct gpt_header *gpt_get_header(struct fdisk_context *cxt, uint64_t lba
 	if (le64_to_cpu(header->my_lba) != lba)
 		goto invalid;
 
+	/* make sure header size is between 92 and sector size bytes */
+	hsz = le32_to_cpu(header->size);
+	if (hsz < GPT_HEADER_MINSZ || hsz > cxt->sector_size)
+		goto invalid;
+
 	return header;
 invalid:
 	free(header);