diff --git a/block/qcow2.c b/block/qcow2.c
index 36395289a9..cc1bfebf29 100644
--- a/block/qcow2.c
+++ b/block/qcow2.c
@@ -445,7 +445,8 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
                       Error **errp)
 {
     BDRVQcowState *s = bs->opaque;
-    int len, i, ret = 0;
+    unsigned int len, i;
+    int ret = 0;
     QCowHeader header;
     QemuOpts *opts;
     Error *local_err = NULL;
@@ -721,8 +722,10 @@ static int qcow2_open(BlockDriverState *bs, QDict *options, int flags,
     /* read the backing file name */
     if (header.backing_file_offset != 0) {
         len = header.backing_file_size;
-        if (len > 1023) {
-            len = 1023;
+        if (len > MIN(1023, s->cluster_size - header.backing_file_offset)) {
+            error_setg(errp, "Backing file name too long");
+            ret = -EINVAL;
+            goto fail;
         }
         ret = bdrv_pread(bs->file, header.backing_file_offset,
                          bs->backing_file, len);
diff --git a/tests/qemu-iotests/080 b/tests/qemu-iotests/080
index 7255b6cca6..f3091a9377 100755
--- a/tests/qemu-iotests/080
+++ b/tests/qemu-iotests/080
@@ -45,6 +45,7 @@ _supported_os Linux
 header_size=104
 
 offset_backing_file_offset=8
+offset_backing_file_size=16
 offset_l1_size=36
 offset_l1_table_offset=40
 offset_refcount_table_offset=48
@@ -135,6 +136,13 @@ poke_file "$TEST_IMG" "$offset_l1_table_offset" "\x12\x34\x56\x78\x90\xab\xcd\xe
 poke_file "$TEST_IMG" "$offset_l1_size" "\x00\x00\x00\x01"
 { $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
 
+echo
+echo "== Invalid backing file size =="
+_make_test_img 64M
+poke_file "$TEST_IMG" "$offset_backing_file_offset" "\x00\x00\x00\x00\x00\x00\x10\x00"
+poke_file "$TEST_IMG" "$offset_backing_file_size" "\xff\xff\xff\xff"
+{ $QEMU_IO -c "read 0 512" $TEST_IMG; } 2>&1 | _filter_qemu_io | _filter_testdir
+
 # success, all done
 echo "*** done"
 rm -f $seq.full
diff --git a/tests/qemu-iotests/080.out b/tests/qemu-iotests/080.out
index 4ec2545051..8103211064 100644
--- a/tests/qemu-iotests/080.out
+++ b/tests/qemu-iotests/080.out
@@ -58,4 +58,9 @@ qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset
 no file open, try 'help open'
 qemu-io: can't open device TEST_DIR/t.qcow2: Invalid L1 table offset
 no file open, try 'help open'
+
+== Invalid backing file size ==
+Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 
+qemu-io: can't open device TEST_DIR/t.qcow2: Backing file name too long
+no file open, try 'help open'
 *** done