[Qemu-devel] [PULL 06/12] block: vmdk - move string allocations from stack to the heap

[Kevin Wolf]

From: Jeff Cody <address@hidden>

Functions 'vmdk_parse_extents' and 'vmdk_create' allocate several
PATH_MAX sized arrays on the stack.  Make these dynamically allocated.

Signed-off-by: Jeff Cody <address@hidden>
Signed-off-by: Kevin Wolf <address@hidden>
---
 block/vmdk.c | 39 +++++++++++++++++++++++----------------
 1 file changed, 23 insertions(+), 16 deletions(-)

diff --git a/block/vmdk.c b/block/vmdk.c
index dc6459c..7d079ad 100644
--- a/block/vmdk.c
+++ b/block/vmdk.c
@@ -792,12 +792,11 @@ static int vmdk_parse_extents(const char *desc, 
BlockDriverState *bs,
     const char *p = desc;
     int64_t sectors = 0;
     int64_t flat_offset;
-    char extent_path[PATH_MAX];
+    char *extent_path;
     BlockDriverState *extent_file;
     BDRVVmdkState *s = bs->opaque;
     VmdkExtent *extent;
 
-
     while (*p) {
         /* parse extent line in one of below formats:
          *
@@ -843,11 +842,13 @@ static int vmdk_parse_extents(const char *desc, 
BlockDriverState *bs,
             return -EINVAL;
         }
 
+        extent_path = g_malloc0(PATH_MAX);
         path_combine(extent_path, sizeof(extent_path),
                 desc_file_path, fname);
         extent_file = NULL;
         ret = bdrv_open(&extent_file, extent_path, NULL, NULL,
                         bs->open_flags | BDRV_O_PROTOCOL, NULL, errp);
+        g_free(extent_path);
         if (ret) {
             return ret;
         }
@@ -1797,10 +1798,15 @@ static int vmdk_create(const char *filename, QemuOpts 
*opts, Error **errp)
     int ret = 0;
     bool flat, split, compress;
     GString *ext_desc_lines;
-    char path[PATH_MAX], prefix[PATH_MAX], postfix[PATH_MAX];
+    char *path = g_malloc0(PATH_MAX);
+    char *prefix = g_malloc0(PATH_MAX);
+    char *postfix = g_malloc0(PATH_MAX);
+    char *desc_line = g_malloc0(BUF_SIZE);
+    char *ext_filename = g_malloc0(PATH_MAX);
+    char *desc_filename = g_malloc0(PATH_MAX);
     const int64_t split_size = 0x80000000;  /* VMDK has constant split size */
     const char *desc_extent_line;
-    char parent_desc_line[BUF_SIZE] = "";
+    char *parent_desc_line = g_malloc0(BUF_SIZE);
     uint32_t parent_cid = 0xffffffff;
     uint32_t number_heads = 16;
     bool zeroed_grain = false;
@@ -1916,33 +1922,27 @@ static int vmdk_create(const char *filename, QemuOpts 
*opts, Error **errp)
         }
         parent_cid = vmdk_read_cid(bs, 0);
         bdrv_unref(bs);
-        snprintf(parent_desc_line, sizeof(parent_desc_line),
+        snprintf(parent_desc_line, BUF_SIZE,
                 "parentFileNameHint=\"%s\"", backing_file);
     }
 
     /* Create extents */
     filesize = total_size;
     while (filesize > 0) {
-        char desc_line[BUF_SIZE];
-        char ext_filename[PATH_MAX];
-        char desc_filename[PATH_MAX];
         int64_t size = filesize;
 
         if (split && size > split_size) {
             size = split_size;
         }
         if (split) {
-            snprintf(desc_filename, sizeof(desc_filename), "%s-%c%03d%s",
+            snprintf(desc_filename, PATH_MAX, "%s-%c%03d%s",
                     prefix, flat ? 'f' : 's', ++idx, postfix);
         } else if (flat) {
-            snprintf(desc_filename, sizeof(desc_filename), "%s-flat%s",
-                    prefix, postfix);
+            snprintf(desc_filename, PATH_MAX, "%s-flat%s", prefix, postfix);
         } else {
-            snprintf(desc_filename, sizeof(desc_filename), "%s%s",
-                    prefix, postfix);
+            snprintf(desc_filename, PATH_MAX, "%s%s", prefix, postfix);
         }
-        snprintf(ext_filename, sizeof(ext_filename), "%s%s",
-                path, desc_filename);
+        snprintf(ext_filename, PATH_MAX, "%s%s", path, desc_filename);
 
         if (vmdk_create_extent(ext_filename, size,
                                flat, compress, zeroed_grain, opts, errp)) {
@@ -1952,7 +1952,7 @@ static int vmdk_create(const char *filename, QemuOpts 
*opts, Error **errp)
         filesize -= size;
 
         /* Format description line */
-        snprintf(desc_line, sizeof(desc_line),
+        snprintf(desc_line, BUF_SIZE,
                     desc_extent_line, size / BDRV_SECTOR_SIZE, desc_filename);
         g_string_append(ext_desc_lines, desc_line);
     }
@@ -2007,6 +2007,13 @@ exit:
     g_free(backing_file);
     g_free(fmt);
     g_free(desc);
+    g_free(path);
+    g_free(prefix);
+    g_free(postfix);
+    g_free(desc_line);
+    g_free(ext_filename);
+    g_free(desc_filename);
+    g_free(parent_desc_line);
     g_string_free(ext_desc_lines, true);
     return ret;
 }
-- 
1.8.3.1