[Qemu-devel] [PATCH for-2.0 16/47] vdi: add bounds checks for blocks_in_image and disk_size header fields (CVE-2014-0144)

[Stefan Hajnoczi <stefanha@redhat.com>]

From: Jeff Cody <jcody@redhat.com>

The maximum blocks_in_image is 0xffffffff / 4, which also limits the
maximum disk_size for a VDI image.

Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vdi.c | 28 +++++++++++++++++++++++++---
 1 file changed, 25 insertions(+), 3 deletions(-)

diff --git a/block/vdi.c b/block/vdi.c
index ac9a025..718884d 100644
--- a/block/vdi.c
+++ b/block/vdi.c
@@ -120,6 +120,12 @@ typedef unsigned char uuid_t[16];
 
 #define VDI_IS_ALLOCATED(X) ((X) < VDI_DISCARDED)
 
+#define VDI_BLOCK_SIZE           (1 * MiB)
+/* max blocks in image is (0xffffffff / 4) */
+#define VDI_BLOCKS_IN_IMAGE_MAX  0x3fffffff
+#define VDI_DISK_SIZE_MAX        ((uint64_t)VDI_BLOCKS_IN_IMAGE_MAX * \
+                                  (uint64_t)VDI_BLOCK_SIZE)
+
 #if !defined(CONFIG_UUID)
 static inline void uuid_generate(uuid_t out)
 {
@@ -385,6 +391,11 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
     vdi_header_print(&header);
 #endif
 
+    if (header.disk_size > VDI_DISK_SIZE_MAX) {
+        ret = -EINVAL;
+        goto fail;
+    }
+
     if (header.disk_size % SECTOR_SIZE != 0) {
         /* 'VBoxManage convertfromraw' can create images with odd disk sizes.
            We accept them but round the disk size to the next multiple of
@@ -420,9 +431,9 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
                    header.sector_size, SECTOR_SIZE);
         ret = -ENOTSUP;
         goto fail;
-    } else if (header.block_size != 1 * MiB) {
+    } else if (header.block_size != VDI_BLOCK_SIZE) {
         error_setg(errp, "unsupported VDI image (sector size %u is not %u)",
-                   header.block_size, 1 * MiB);
+                   header.block_size, VDI_BLOCK_SIZE);
         ret = -ENOTSUP;
         goto fail;
     } else if (header.disk_size >
@@ -441,6 +452,10 @@ static int vdi_open(BlockDriverState *bs, QDict *options, int flags,
         error_setg(errp, "unsupported VDI image (non-NULL parent UUID)");
         ret = -ENOTSUP;
         goto fail;
+    } else if (header.blocks_in_image > VDI_BLOCKS_IN_IMAGE_MAX) {
+        error_setg(errp, "unsupported VDI image (too many blocks)");
+        ret = -ENOTSUP;
+        goto fail;
     }
 
     bs->total_sectors = header.disk_size / SECTOR_SIZE;
@@ -689,11 +704,17 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options,
         options++;
     }
 
+    if (bytes > VDI_DISK_SIZE_MAX) {
+        result = -EINVAL;
+        goto exit;
+    }
+
     fd = qemu_open(filename,
                    O_WRONLY | O_CREAT | O_TRUNC | O_BINARY | O_LARGEFILE,
                    0644);
     if (fd < 0) {
-        return -errno;
+        result = -errno;
+        goto exit;
     }
 
     /* We need enough blocks to store the given disk size,
@@ -754,6 +775,7 @@ static int vdi_create(const char *filename, QEMUOptionParameter *options,
         result = -errno;
     }
 
+exit:
     return result;
 }
 
-- 
1.8.5.3