From 975a7bd2280db5a8db96a92ff0811e08431a64c7 Mon Sep 17 00:00:00 2001 From: Connor Kuehl Date: Thu, 13 Aug 2020 08:47:22 -0500 Subject: [PATCH] block: Raise an error when backing file parameter is an empty string Providing an empty string for the backing file parameter like so: qemu-img create -f qcow2 -b '' /tmp/foo allows the flow of control to reach and subsequently fail an assert statement because passing an empty string to bdrv_get_full_backing_filename_from_filename() simply results in NULL being returned without an error being raised. To fix this, let's check for an empty string when getting the value from the opts list. Reported-by: Attila Fazekas Fixes: https://bugzilla.redhat.com/1809553 Signed-off-by: Connor Kuehl Message-Id: <20200813134722.802180-1-ckuehl@redhat.com> Signed-off-by: Kevin Wolf --- block.c | 4 ++++ tests/qemu-iotests/049 | 4 ++++ tests/qemu-iotests/049.out | 5 +++++ 3 files changed, 13 insertions(+) diff --git a/block.c b/block.c index 2ba76b2c36..b204b93a2e 100644 --- a/block.c +++ b/block.c @@ -6119,6 +6119,10 @@ void bdrv_img_create(const char *filename, const char *fmt, "same filename as the backing file"); goto out; } + if (backing_file[0] == '\0') { + error_setg(errp, "Expected backing file name, got empty string"); + goto out; + } } backing_fmt = qemu_opt_get(opts, BLOCK_OPT_BACKING_FMT); diff --git a/tests/qemu-iotests/049 b/tests/qemu-iotests/049 index 051a1c79e0..82b1e6c202 100755 --- a/tests/qemu-iotests/049 +++ b/tests/qemu-iotests/049 @@ -119,6 +119,10 @@ test_qemu_img create -f $IMGFMT -o compat=1.1,lazy_refcounts=on "$TEST_IMG" 64M test_qemu_img create -f $IMGFMT -o compat=0.10,lazy_refcounts=off "$TEST_IMG" 64M test_qemu_img create -f $IMGFMT -o compat=0.10,lazy_refcounts=on "$TEST_IMG" 64M +echo "== Expect error when backing file name is empty string ==" +echo +test_qemu_img create -f $IMGFMT -b '' $TEST_IMG 1M + # success, all done echo "*** done" rm -f $seq.full diff --git a/tests/qemu-iotests/049.out b/tests/qemu-iotests/049.out index a7e220830d..b1d8fd9107 100644 --- a/tests/qemu-iotests/049.out +++ b/tests/qemu-iotests/049.out @@ -209,4 +209,9 @@ qemu-img create -f qcow2 -o compat=0.10,lazy_refcounts=on TEST_DIR/t.qcow2 64M Formatting 'TEST_DIR/t.qcow2', fmt=qcow2 cluster_size=65536 extended_l2=off compression_type=zlib size=67108864 compat=0.10 lazy_refcounts=on refcount_bits=16 qemu-img: TEST_DIR/t.qcow2: Lazy refcounts only supported with compatibility level 1.1 and above (use version=v3 or greater) +== Expect error when backing file name is empty string == + +qemu-img create -f qcow2 -b TEST_DIR/t.qcow2 1M +qemu-img: TEST_DIR/t.qcow2: Expected backing file name, got empty string + *** done