[Qemu-devel] [PATCH v3 16/21] vdi: Handle failure for potentially large allocations

[Kevin Wolf <kwolf@redhat.com>]

Some code in the block layer makes potentially huge allocations. Failure
is not completely unexpected there, so avoid aborting qemu and handle
out-of-memory situations gracefully.

This patch addresses the allocations in the vdi block driver.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
---
 block/vdi.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index 27737af..1f76441 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -293,7 +293,12 @@ static int vdi_check(BlockDriverState *bs, BdrvCheckResult *res,
         return -ENOTSUP;
     }
 
-    bmap = g_malloc(s->header.blocks_in_image * sizeof(uint32_t));
+    bmap = g_try_malloc(s->header.blocks_in_image * sizeof(uint32_t));
+    if (s->header.blocks_in_image && bmap == NULL) {
+        res->check_errors++;
+        return -ENOMEM;
+    }
+
     memset(bmap, 0xff, s->header.blocks_in_image * sizeof(uint32_t));
 
     /* Check block map and value of blocks_allocated. */
@@ -472,7 +477,12 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
 
     bmap_size = header.blocks_in_image * sizeof(uint32_t);
     bmap_size = (bmap_size + SECTOR_SIZE - 1) / SECTOR_SIZE;
-    s->bmap = g_malloc(bmap_size * SECTOR_SIZE);
+    s->bmap = qemu_try_blockalign(bs->file, bmap_size * SECTOR_SIZE);
+    if (s->bmap == NULL) {
+        ret = -ENOMEM;
+        goto fail;
+    }
+
     ret = bdrv_read(bs->file, s->bmap_sector, (uint8_t *)s->bmap, bmap_size);
     if (ret < 0) {
         goto fail_free_bmap;
@@ -487,7 +497,7 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     return 0;
 
  fail_free_bmap:
-    g_free(s->bmap);
+    qemu_vfree(s->bmap);
 
  fail:
     return ret;
@@ -760,7 +770,11 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options,
     }
 
     if (bmap_size > 0) {
-        uint32_t *bmap = g_malloc0(bmap_size);
+        uint32_t *bmap = g_try_malloc0(bmap_size);
+        if (bmap == NULL) {
+            result = -ENOMEM;
+            goto close_and_exit;
+        }
         for (i = 0; i < blocks; i++) {
             if (image_type == VDI_TYPE_STATIC) {
                 bmap[i] = i;
@@ -796,7 +810,7 @@ static void vdi_close(BlockDriverState *bs)
 {
     BDRVVdiState *s = bs->opaque;
 
-    g_free(s->bmap);
+    qemu_vfree(s->bmap);
 
     migrate_del_blocker(s->migration_blocker);
     error_free(s->migration_blocker);
-- 
1.8.3.1