From: Kevin Wolf <kwolf@redhat.com>
Date: Wed, 26 Mar 2014 13:06:06 +0100
Subject: [PATCH] qcow2: Check maximum L1 size in qcow2_snapshot_load_tmp()
 (CVE-2014-0143)

This avoids an unbounded allocation.

Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: Max Reitz <mreitz@redhat.com>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
(cherry picked from commit 6a83f8b5bec6f59e56cc49bd49e4c3f8f805d56f)

Conflicts:
	block/qcow2.c
	tests/qemu-iotests/080
	tests/qemu-iotests/080.out
---
 block/qcow2-snapshot.c | 4 ++++
 block/qcow2.c          | 4 +---
 block/qcow2.h          | 4 ++++
 3 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/block/qcow2-snapshot.c b/block/qcow2-snapshot.c
index dc8736a..d2c956c 100644
--- a/block/qcow2-snapshot.c
+++ b/block/qcow2-snapshot.c
@@ -622,6 +622,10 @@ int qcow2_snapshot_load_tmp(BlockDriverState *bs, const char *snapshot_name)
     sn = &s->snapshots[snapshot_index];
 
     /* Allocate and read in the snapshot's L1 table */
+    if (sn->l1_size > QCOW_MAX_L1_SIZE) {
+        fprintf(stderr, "Snapshot L1 table too large");
+        return -EFBIG;
+    }
     new_l1_bytes = sn->l1_size * sizeof(uint64_t);
     new_l1_table = g_malloc0(align_offset(new_l1_bytes, 512));
 
diff --git a/block/qcow2.c b/block/qcow2.c
index c9beb01..5dfd5ec 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -516,9 +516,7 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags)
     }
 
     /* read the level 1 table */
-    if (header.l1_size > 0x2000000) {
-        /* 32 MB L1 table is enough for 2 PB images at 64k cluster size
-         * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
+    if (header.l1_size > QCOW_MAX_L1_SIZE) {
         fprintf(stderr, "Active L1 table too large");
         ret = -EFBIG;
         goto fail;
diff --git a/block/qcow2.h b/block/qcow2.h
index baf62a0..0912488 100644
--- a/block/qcow2.h
+++ b/block/qcow2.h
@@ -44,6 +44,10 @@
  * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
 #define QCOW_MAX_REFTABLE_SIZE 0x800000
 
+/* 32 MB L1 table is enough for 2 PB images at 64k cluster size
+ * (128 GB for 512 byte clusters, 2 EB for 2 MB clusters) */
+#define QCOW_MAX_L1_SIZE 0x2000000
+
 /* indicate that the refcount of the referenced cluster is exactly one. */
 #define QCOW_OFLAG_COPIED     (1LL << 63)
 /* indicate that the cluster is compressed (they never have the copied flag) */