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qemu.35260
qcow2-Don-t-open-data_file-with-BDRV_O_N.patch
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File qcow2-Don-t-open-data_file-with-BDRV_O_N.patch of Package qemu.35260
From: Kevin Wolf <kwolf@redhat.com> Date: Thu, 11 Apr 2024 15:06:01 +0200 Subject: qcow2: Don't open data_file with BDRV_O_NO_IO (bsc#1227322, CVE-2024-4467) One use case for 'qemu-img info' is verifying that untrusted images don't reference an unwanted external file, be it as a backing file or an external data file. To make sure that calling 'qemu-img info' can't already have undesired side effects with a malicious image, just don't open the data file at all with BDRV_O_NO_IO. If nothing ever tries to do I/O, we don't need to have it open. This changes the output of iotests case 061, which used 'qemu-img info' to show that opening an image with an invalid data file fails. After this patch, it succeeds. Replace this part of the test with a qemu-io call, but keep the final 'qemu-img info' to show that the invalid data file is correctly displayed in the output. Fixes: CVE-2024-4467 Cc: qemu-stable@nongnu.org Signed-off-by: Kevin Wolf <kwolf@redhat.com> Reviewed-by: Eric Blake <eblake@redhat.com> Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com> Reviewed-by: Hanna Czenczek <hreitz@redhat.com> (cherry picked from commit bd385a5298d7062668e804d73944d52aec9549f1) References: bsc#1227322 References: CVE-2024-4467 Signed-off-by: Dario Faggioli <dfaggioli@suse.com> --- block/qcow2.c | 17 ++++++++++++++++- tests/qemu-iotests/061 | 6 ++++-- tests/qemu-iotests/061.out | 8 ++++++-- 3 files changed, 26 insertions(+), 5 deletions(-) diff --git a/block/qcow2.c b/block/qcow2.c index a934db4cf6ac5e8e8019334eb9ff..fecb882a2cbb8fe8b9896b7767f3 100644 --- a/block/qcow2.c +++ b/block/qcow2.c @@ -1611,7 +1611,22 @@ static int coroutine_fn qcow2_do_open(BlockDriverState *bs, QDict *options, goto fail; } - if (open_data_file) { + if (open_data_file && (flags & BDRV_O_NO_IO)) { + /* + * Don't open the data file for 'qemu-img info' so that it can be used + * to verify that an untrusted qcow2 image doesn't refer to external + * files. + * + * Note: This still makes has_data_file() return true. + */ + if (s->incompatible_features & QCOW2_INCOMPAT_DATA_FILE) { + s->data_file = NULL; + } else { + s->data_file = bs->file; + } + qdict_extract_subqdict(options, NULL, "data-file."); + qdict_del(options, "data-file"); + } else if (open_data_file) { /* Open external data file */ s->data_file = bdrv_open_child(NULL, options, "data-file", bs, &child_of_bds, BDRV_CHILD_DATA, diff --git a/tests/qemu-iotests/061 b/tests/qemu-iotests/061 index 5747beb7ed60cd96f2ce6f836589..cd98f716c6f6e05b7acee40f90ee 100755 --- a/tests/qemu-iotests/061 +++ b/tests/qemu-iotests/061 @@ -318,12 +318,14 @@ $QEMU_IMG amend -o "data_file=foo" "$TEST_IMG" echo _make_test_img -o "compat=1.1,data_file=$TEST_IMG.data" 64M $QEMU_IMG amend -o "data_file=foo" "$TEST_IMG" -_img_info --format-specific +$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt +$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts echo $QEMU_IMG amend -o "data_file=" --image-opts "data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -_img_info --format-specific +$QEMU_IO -c "read 0 4k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt +$QEMU_IO -c "open -o data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" -c "read 0 4k" | _filter_qemu_io TEST_IMG="data-file.filename=$TEST_IMG.data,file.filename=$TEST_IMG" _img_info --format-specific --image-opts echo diff --git a/tests/qemu-iotests/061.out b/tests/qemu-iotests/061.out index ee30da266514537bd3e6885a5958..8ce296b0a14ad57bdab1ec6f3120 100644 --- a/tests/qemu-iotests/061.out +++ b/tests/qemu-iotests/061.out @@ -544,7 +544,9 @@ Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 qemu-img: data-file can only be set for images that use an external data file Formatting 'TEST_DIR/t.IMGFMT', fmt=IMGFMT size=67108864 data_file=TEST_DIR/t.IMGFMT.data -qemu-img: Could not open 'TEST_DIR/t.IMGFMT': Could not open 'foo': No such file or directory +qemu-io: can't open device TEST_DIR/t.IMGFMT: Could not open 'foo': No such file or directory +read 4096/4096 bytes at offset 0 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) image: TEST_DIR/t.IMGFMT file format: IMGFMT virtual size: 64 MiB (67108864 bytes) @@ -559,7 +561,9 @@ Format specific information: corrupt: false extended l2: false -qemu-img: Could not open 'TEST_DIR/t.IMGFMT': 'data-file' is required for this image +qemu-io: can't open device TEST_DIR/t.IMGFMT: 'data-file' is required for this image +read 4096/4096 bytes at offset 0 +4 KiB, X ops; XX:XX:XX.X (XXX YYY/sec and XXX ops/sec) image: TEST_DIR/t.IMGFMT file format: IMGFMT virtual size: 64 MiB (67108864 bytes)
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