1 files changed, 39 insertions, 13 deletions

diff --git a/qemu-img.c b/qemu-img.c
index 86127f0b11..01cc0d35ad 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -332,8 +332,9 @@ static int img_create(int argc, char **argv)
     /* Get image size, if specified */
     if (optind < argc) {
         int64_t sval;
-        sval = strtosz_suffix(argv[optind++], NULL, STRTOSZ_DEFSUFFIX_B);
-        if (sval < 0) {
+        char *end;
+        sval = strtosz_suffix(argv[optind++], &end, STRTOSZ_DEFSUFFIX_B);
+        if (sval < 0 || *end) {
             error_report("Invalid image size specified! You may use k, M, G or "
                   "T suffixes for ");
             error_report("kilobytes, megabytes, gigabytes and terabytes.");
@@ -710,8 +711,9 @@ static int img_convert(int argc, char **argv)
         case 'S':
         {
             int64_t sval;
-            sval = strtosz_suffix(optarg, NULL, STRTOSZ_DEFSUFFIX_B);
-            if (sval < 0) {
+            char *end;
+            sval = strtosz_suffix(optarg, &end, STRTOSZ_DEFSUFFIX_B);
+            if (sval < 0 || *end) {
                 error_report("Invalid minimum zero buffer size for sparse output specified");
                 return 1;
             }
@@ -1418,6 +1420,8 @@ static int img_rebase(int argc, char **argv)
      */
     if (!unsafe) {
         uint64_t num_sectors;
+        uint64_t old_backing_num_sectors;
+        uint64_t new_backing_num_sectors;
         uint64_t sector;
         int n;
         uint8_t * buf_old;
@@ -1428,6 +1432,8 @@ static int img_rebase(int argc, char **argv)
         buf_new = qemu_blockalign(bs, IO_BUF_SIZE);
 
         bdrv_get_geometry(bs, &num_sectors);
+        bdrv_get_geometry(bs_old_backing, &old_backing_num_sectors);
+        bdrv_get_geometry(bs_new_backing, &new_backing_num_sectors);
 
         local_progress = (float)100 /
             (num_sectors / MIN(num_sectors, IO_BUF_SIZE / 512));
@@ -1446,16 +1452,36 @@ static int img_rebase(int argc, char **argv)
                 continue;
             }
 
-            /* Read old and new backing file */
-            ret = bdrv_read(bs_old_backing, sector, buf_old, n);
-            if (ret < 0) {
-                error_report("error while reading from old backing file");
-                goto out;
+            /*
+             * Read old and new backing file and take into consideration that
+             * backing files may be smaller than the COW image.
+             */
+            if (sector >= old_backing_num_sectors) {
+                memset(buf_old, 0, n * BDRV_SECTOR_SIZE);
+            } else {
+                if (sector + n > old_backing_num_sectors) {
+                    n = old_backing_num_sectors - sector;
+                }
+
+                ret = bdrv_read(bs_old_backing, sector, buf_old, n);
+                if (ret < 0) {
+                    error_report("error while reading from old backing file");
+                    goto out;
+                }
             }
-            ret = bdrv_read(bs_new_backing, sector, buf_new, n);
-            if (ret < 0) {
-                error_report("error while reading from new backing file");
-                goto out;
+
+            if (sector >= new_backing_num_sectors) {
+                memset(buf_new, 0, n * BDRV_SECTOR_SIZE);
+            } else {
+                if (sector + n > new_backing_num_sectors) {
+                    n = new_backing_num_sectors - sector;
+                }
+
+                ret = bdrv_read(bs_new_backing, sector, buf_new, n);
+                if (ret < 0) {
+                    error_report("error while reading from new backing file");
+                    goto out;
+                }
             }
 
             /* If they differ, we need to write to the COW file */