semantic: 0.085 files: 0.076 mistranslation: 0.075 device: 0.074 performance: 0.066 architecture: 0.066 graphic: 0.059 PID: 0.053 user-level: 0.049 ppc: 0.046 network: 0.045 assembly: 0.043 virtual: 0.037 permissions: 0.036 boot: 0.033 debug: 0.033 register: 0.031 x86: 0.030 vnc: 0.029 risc-v: 0.028 socket: 0.025 arm: 0.023 i386: 0.023 kernel: 0.019 peripherals: 0.016 VMM: 0.014 TCG: 0.012 hypervisor: 0.010 KVM: 0.008 Data corruption with qcow2 images Steps to reproduce: ``` # Create an example file with old version of qemu-img and fill it with random data. $ qemu-img-8.2.2 create -f qcow2 file.qcow2 600000000000 $ qemu-nbd-8.2.2 -c /dev/nbd0 file.qcow2 $ dd if=/dev/random of=/dev/nbd0 bs=1000000 count=600000 $ qemu-nbd-8.2.2 -d /dev/nbd0 /dev/nbd0 disconnected # Get the correct checksum of both qcow2 file and its contents $ sha256sum -b file.qcow2 ca471f6822af4fcf3c81bc5cc671493be06a837b71b43c1f747042759da587b9 *file.qcow2 $ qemu-nbd-8.2.2 -r -c /dev/nbd0 file.qcow2 $ sha256sum -b /dev/nbd0 5dac11e88f891740da3b655588b2e62037962d1ba6377efce30124d6224dd0d1 */dev/nbd0 $ qemu-nbd-8.2.2 -d /dev/nbd0 /dev/nbd0 disconnected # Use the qcow2 file with new version. # We're using qemu-nbd here, but the same happens when qcow2 is attached to a guest # running in the new version qemu-system-86_64-9.1.1 and can be seen through guest's # /dev/vda. # Note that the checksum is different than before, and also non-deterministic # (running sha256sum twice produces different results even though the file is # read-only and hasn't changed). $ sha256sum -b file.qcow2 ca471f6822af4fcf3c81bc5cc671493be06a837b71b43c1f747042759da587b9 *file.qcow2 $ qemu-nbd-9.1.1 -r -c /dev/nbd0 file.qcow2 $ sha256sum -b /dev/nbd0 1793a38b9b964d3fc643629284722373e9d5dedea68e35900ace777b57688926 */dev/nbd0 $ sha256sum -b /dev/nbd0 98f900f9cd174493d0bfcf06e2bc86f5ee99dfa04c90d6832fa941e384b62d49 */dev/nbd0 $ qemu-nbd-9.1.1 -d /dev/nbd0 /dev/nbd0 disconnected $ sha256sum -b file.qcow2 ca471f6822af4fcf3c81bc5cc671493be06a837b71b43c1f747042759da587b9 *file.qcow2 ``` Additional information: No errors in either host or guest logs. When using a qcow2 with an actual filesystem, you may see reports of corruption from the filesystem driver.