Patchwork [for-2.0,17/47] vhdx: Bounds checking for block_size and logical_sector_size (CVE-2014-0148)

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Submitter Stefan Hajnoczi
Date March 26, 2014, 12:05 p.m.
Message ID <1395835569-21193-18-git-send-email-stefanha@redhat.com>
Download mbox | patch
Permalink /patch/333945/
State New
Headers show

Comments

Stefan Hajnoczi - March 26, 2014, 12:05 p.m.
From: Jeff Cody <jcody@redhat.com>

Other variables (e.g. sectors_per_block) are calculated using these
variables, and if not range-checked illegal values could be obtained
causing infinite loops and other potential issues when calculating
BAT entries.

The 1.00 VHDX spec requires BlockSize to be min 1MB, max 256MB.
LogicalSectorSize is required to be either 512 or 4096 bytes.

Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
---
 block/vhdx.c | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)
Max Reitz - March 26, 2014, 8:26 p.m.
On 26.03.2014 13:05, Stefan Hajnoczi wrote:
> From: Jeff Cody <jcody@redhat.com>
>
> Other variables (e.g. sectors_per_block) are calculated using these
> variables, and if not range-checked illegal values could be obtained
> causing infinite loops and other potential issues when calculating
> BAT entries.
>
> The 1.00 VHDX spec requires BlockSize to be min 1MB, max 256MB.
> LogicalSectorSize is required to be either 512 or 4096 bytes.
>
> Reported-by: Kevin Wolf <kwolf@redhat.com>
> Signed-off-by: Jeff Cody <jcody@redhat.com>
> Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> ---
>   block/vhdx.c | 12 ++++++++++--
>   1 file changed, 10 insertions(+), 2 deletions(-)

Reviewed-by: Max Reitz <mreitz@redhat.com>

Patch

diff --git a/block/vhdx.c b/block/vhdx.c
index 5390ba6..509baaf 100644
--- a/block/vhdx.c
+++ b/block/vhdx.c
@@ -780,12 +780,20 @@  static int vhdx_parse_metadata(BlockDriverState *bs, BDRVVHDXState *s)
     le32_to_cpus(&s->logical_sector_size);
     le32_to_cpus(&s->physical_sector_size);
 
-    if (s->logical_sector_size == 0 || s->params.block_size == 0) {
+    if (s->params.block_size < VHDX_BLOCK_SIZE_MIN ||
+        s->params.block_size > VHDX_BLOCK_SIZE_MAX) {
         ret = -EINVAL;
         goto exit;
     }
 
-    /* both block_size and sector_size are guaranteed powers of 2 */
+    /* only 2 supported sector sizes */
+    if (s->logical_sector_size != 512 && s->logical_sector_size != 4096) {
+        ret = -EINVAL;
+        goto exit;
+    }
+
+    /* Both block_size and sector_size are guaranteed powers of 2, below.
+       Due to range checks above, s->sectors_per_block can never be < 256 */
     s->sectors_per_block = s->params.block_size / s->logical_sector_size;
     s->chunk_ratio = (VHDX_MAX_SECTORS_PER_BLOCK) *
                      (uint64_t)s->logical_sector_size /