libblkid: (gpt) don't modify in memory buffers

LIBBLKID_DEBUG=0xffff blkid -p ....

gpt: ---> call probefunc()
	reuse buffer: off=0 len=1024 pr=0xb0b690
	reuse buffer: off=0 len=1024 pr=0xb0b690
	reuse buffer: off=1024 len=16384 pr=0xb0b690
GPT entries corrupted
	reuse buffer: off=10737417728 len=512 pr=0xb0b690
	reuse buffer: off=10737401344 len=16384 pr=0xb0b690
GPT entries corrupted
gpt: <--- (rc = 1)

Reported-by: Dave Reisner <d@falconindy.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/libblkid/src/partitions/gpt.c b/libblkid/src/partitions/gpt.c
index ccade6b54e2ca24885eefe340a8578c228800c4a..98e82bfd2f9ac0e60e312fbe52a39de40de76156 100644 (file)
--- a/libblkid/src/partitions/gpt.c
+++ b/libblkid/src/partitions/gpt.c
@@ -226,15 +226,15 @@ static struct gpt_header *get_gpt_header(
                return NULL;
 
        /* Header has to be verified when header_crc32 is zero */
-       orgcrc = le32_to_cpu(h->header_crc32);
+       orgcrc = h->header_crc32;
        h->header_crc32 = 0;
-
        crc = count_crc32((unsigned char *) h, hsz);
-       if (crc != orgcrc) {
+       h->header_crc32 = orgcrc;
+
+       if (crc != le32_to_cpu(orgcrc)) {
                DBG(DEBUG_LOWPROBE, printf("GPT header corrupted\n"));
                return NULL;
        }
-       h->header_crc32 = cpu_to_le32(orgcrc);
 
        /* Valid header has to be at MyLBA */
        if (le64_to_cpu(h->my_lba) != lba) {
@@ -300,7 +300,7 @@ static int probe_gpt_pt(blkid_probe pr,
        blkid_partlist ls;
        uint64_t fu, lu;
        uint32_t ssf, i;
-
+       efi_guid_t guid;
 
        if (last_lba(pr, &lastlba))
                goto nothing;
@@ -369,14 +369,13 @@ static int probe_gpt_pt(blkid_probe pr,
                        (unsigned char *) e->partition_name,
                        sizeof(e->partition_name), BLKID_ENC_UTF16LE);
 
-               swap_efi_guid(&e->unique_partition_guid);
-               swap_efi_guid(&e->partition_type_guid);
-
-               blkid_partition_set_uuid(par,
-                       (const unsigned char *) &e->unique_partition_guid);
+               guid = e->unique_partition_guid;
+               swap_efi_guid(&guid);
+               blkid_partition_set_uuid(par, (const unsigned char *) &guid);
 
-               blkid_partition_set_type_uuid(par,
-                       (const unsigned char *) &e->partition_type_guid);
+               guid = e->partition_type_guid;
+               swap_efi_guid(&guid);
+               blkid_partition_set_type_uuid(par, (const unsigned char *) &guid);
 
                blkid_partition_set_flags(par, e->attributes);
        }