block: VHDX endian fixes

This patch contains several changes for endian conversion fixes for
VHDX, particularly for big-endian machines (multibyte values in VHDX are
all on disk in LE format).

Tests were done with existing qemu-iotests on an IBM POWER7 (8406-71Y).
This includes sample images created by Hyper-V, both with dirty logs and
without.

In addition, VHDX image files created (and written to) on a BE machine
were tested on a LE machine, and vice-versa.

Reported-by: Markus Armburster <armbru@redhat.com>
Reported-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

1 files changed, 25 insertions, 18 deletions

diff --git a/block/vhdx-log.c b/block/vhdx-log.c
index 7c2630d659..0088be8747 100644
--- a/block/vhdx-log.c
+++ b/block/vhdx-log.c
@@ -84,6 +84,7 @@ static int vhdx_log_peek_hdr(BlockDriverState *bs, VHDXLogEntries *log,
     if (ret < 0) {
         goto exit;
     }
+    vhdx_log_entry_hdr_le_import(hdr);
 
 exit:
     return ret;
@@ -211,7 +212,7 @@ static bool vhdx_log_hdr_is_valid(VHDXLogEntries *log, VHDXLogEntryHeader *hdr,
 {
     int valid = false;
 
-    if (memcmp(&hdr->signature, "loge", 4)) {
+    if (hdr->signature != VHDX_LOG_SIGNATURE) {
         goto exit;
     }
 
@@ -275,12 +276,12 @@ static bool vhdx_log_desc_is_valid(VHDXLogDescriptor *desc,
         goto exit;
     }
 
-    if (!memcmp(&desc->signature, "zero", 4)) {
+    if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
         if (desc->zero_length % VHDX_LOG_SECTOR_SIZE == 0) {
             /* valid */
             ret = true;
         }
-    } else if (!memcmp(&desc->signature, "desc", 4)) {
+    } else if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
             /* valid */
             ret = true;
     }
@@ -327,13 +328,15 @@ static int vhdx_compute_desc_sectors(uint32_t desc_cnt)
  * passed into this function. Each descriptor will also be validated,
  * and error returned if any are invalid. */
 static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
-                              VHDXLogEntries *log, VHDXLogDescEntries **buffer)
+                              VHDXLogEntries *log, VHDXLogDescEntries **buffer,
+                              bool convert_endian)
 {
     int ret = 0;
     uint32_t desc_sectors;
     uint32_t sectors_read;
     VHDXLogEntryHeader hdr;
     VHDXLogDescEntries *desc_entries = NULL;
+    VHDXLogDescriptor desc;
     int i;
 
     assert(*buffer == NULL);
@@ -342,7 +345,7 @@ static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
     if (ret < 0) {
         goto exit;
     }
-    vhdx_log_entry_hdr_le_import(&hdr);
+
     if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
         ret = -EINVAL;
         goto exit;
@@ -363,12 +366,19 @@ static int vhdx_log_read_desc(BlockDriverState *bs, BDRVVHDXState *s,
 
     /* put in proper endianness, and validate each desc */
     for (i = 0; i < hdr.descriptor_count; i++) {
-        vhdx_log_desc_le_import(&desc_entries->desc[i]);
-        if (vhdx_log_desc_is_valid(&desc_entries->desc[i], &hdr) == false) {
+        desc = desc_entries->desc[i];
+        vhdx_log_desc_le_import(&desc);
+        if (convert_endian) {
+            desc_entries->desc[i] = desc;
+        }
+        if (vhdx_log_desc_is_valid(&desc, &hdr) == false) {
             ret = -EINVAL;
             goto free_and_exit;
         }
     }
+    if (convert_endian) {
+        desc_entries->hdr = hdr;
+    }
 
     *buffer = desc_entries;
     goto exit;
@@ -403,7 +413,7 @@ static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc,
 
     buffer = qemu_blockalign(bs, VHDX_LOG_SECTOR_SIZE);
 
-    if (!memcmp(&desc->signature, "desc", 4)) {
+    if (desc->signature == VHDX_LOG_DESC_SIGNATURE) {
         /* data sector */
         if (data == NULL) {
             ret = -EFAULT;
@@ -431,7 +441,7 @@ static int vhdx_log_flush_desc(BlockDriverState *bs, VHDXLogDescriptor *desc,
 
         memcpy(buffer+offset, &desc->trailing_bytes, 4);
 
-    } else if (!memcmp(&desc->signature, "zero", 4)) {
+    } else if (desc->signature == VHDX_LOG_ZERO_SIGNATURE) {
         /* write 'count' sectors of sector */
         memset(buffer, 0, VHDX_LOG_SECTOR_SIZE);
         count = desc->zero_length / VHDX_LOG_SECTOR_SIZE;
@@ -498,13 +508,13 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
             goto exit;
         }
 
-        ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries);
+        ret = vhdx_log_read_desc(bs, s, &logs->log, &desc_entries, true);
         if (ret < 0) {
             goto exit;
         }
 
         for (i = 0; i < desc_entries->hdr.descriptor_count; i++) {
-            if (!memcmp(&desc_entries->desc[i].signature, "desc", 4)) {
+            if (desc_entries->desc[i].signature == VHDX_LOG_DESC_SIGNATURE) {
                 /* data sector, so read a sector to flush */
                 ret = vhdx_log_read_sectors(bs, &logs->log, &sectors_read,
                                             data, 1, false);
@@ -515,6 +525,7 @@ static int vhdx_log_flush(BlockDriverState *bs, BDRVVHDXState *s,
                     ret = -EINVAL;
                     goto exit;
                 }
+                vhdx_log_data_le_import(data);
             }
 
             ret = vhdx_log_flush_desc(bs, &desc_entries->desc[i], data);
@@ -563,9 +574,6 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
         goto inc_and_exit;
     }
 
-    vhdx_log_entry_hdr_le_import(&hdr);
-
-
     if (vhdx_log_hdr_is_valid(log, &hdr, s) == false) {
         goto inc_and_exit;
     }
@@ -578,13 +586,13 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
 
     desc_sectors = vhdx_compute_desc_sectors(hdr.descriptor_count);
 
-    /* Read desc sectors, and calculate log checksum */
+    /* Read all log sectors, and calculate log checksum */
 
     total_sectors = hdr.entry_length / VHDX_LOG_SECTOR_SIZE;
 
 
     /* read_desc() will increment the read idx */
-    ret = vhdx_log_read_desc(bs, s, log, &desc_buffer);
+    ret = vhdx_log_read_desc(bs, s, log, &desc_buffer, false);
     if (ret < 0) {
         goto free_and_exit;
     }
@@ -607,7 +615,7 @@ static int vhdx_validate_log_entry(BlockDriverState *bs, BDRVVHDXState *s,
         }
     }
     crc ^= 0xffffffff;
-    if (crc != desc_buffer->hdr.checksum) {
+    if (crc != hdr.checksum) {
         goto free_and_exit;
     }
 
@@ -967,7 +975,6 @@ static int vhdx_log_write(BlockDriverState *bs, BDRVVHDXState *s,
      * last data sector */
     vhdx_update_checksum(buffer, total_length,
                          offsetof(VHDXLogEntryHeader, checksum));
-    cpu_to_le32s((uint32_t *)(buffer + 4));
 
     /* now write to the log */
     ret = vhdx_log_write_sectors(bs, &s->log, &sectors_written, buffer,