[Bug 1681439] Re: qemu-system-x86_64: hw/ide/core.c:685: ide_cancel_dma_sync: Assertion `s->bus->dma->aiocb == NULL' failed.

[Bugs SysSec]

We found a reproducer during fuzzing:

```
qemu-system-x86_64: hw/ide/core.c:724: ide_cancel_dma_sync: Assertion 
`s->bus->dma->aiocb == NULL' failed.
```

To reproduce run the QEMU with the following command line:
```
qemu-system-x86_64 -cdrom hypertrash.iso -nographic -m 100 -enable-kvm -net 
none -hda hda.img
```

QEMU Version:
```
# qemu-5.0.0
$ ./configure --target-list=x86_64-softmmu --enable-sanitizers; make
$ x86_64-softmmu/qemu-system-x86_64 --version
QEMU emulator version 5.0.0
Copyright (c) 2003-2020 Fabrice Bellard and the QEMU Project developers
```

To create disk image run:
```
qemu-img create hda.img 10M
```


** Attachment added: "ide_assert1.zip"
   
https://bugs.launchpad.net/qemu/+bug/1681439/+attachment/5384437/+files/ide_assert1.zip

** Changed in: qemu
       Status: Expired => New

-- 
You received this bug notification because you are a member of qemu-
devel-ml, which is subscribed to QEMU.
https://bugs.launchpad.net/bugs/1681439

Title:
  qemu-system-x86_64: hw/ide/core.c:685: ide_cancel_dma_sync: Assertion
  `s->bus->dma->aiocb == NULL' failed.

Status in QEMU:
  New

Bug description:
  Since upgrading to QEMU 2.8.0, my Windows 7 64-bit virtual machines
  started crashing due to the assertion quoted in the summary failing.
  The assertion in question was added by commit 9972354856 ("block: add
  BDS field to count in-flight requests").  My tests show that setting
  discard=unmap is needed to reproduce the issue.  Speaking of
  reproduction, it is a bit flaky, because I have been unable to come up
  with specific instructions that would allow the issue to be triggered
  outside of my environment, but I do have a semi-sane way of testing that
  appears to depend on a specific initial state of data on the underlying
  storage volume, actions taken within the VM and waiting for about 20
  minutes.

  Here is the shortest QEMU command line that I managed to reproduce the
  bug with:

      qemu-system-x86_64 \
          -machine pc-i440fx-2.7,accel=kvm \
          -m 3072 \
          -drive file=/dev/lvm/qemu,format=raw,if=ide,discard=unmap \
        -netdev tap,id=hostnet0,ifname=tap0,script=no,downscript=no,vhost=on \
          -device virtio-net-pci,netdev=hostnet0 \
        -vnc :0

  The underlying storage (/dev/lvm/qemu) is a thin LVM snapshot.

  QEMU was compiled using:

      ./configure --python=/usr/bin/python2.7 --target-list=x86_64-softmmu
      make -j3

  My virtualization environment is not really a critical one and
  reproduction is not that much of a hassle, so if you need me to gather
  further diagnostic information or test patches, I will be happy to help.

To manage notifications about this bug go to:
https://bugs.launchpad.net/qemu/+bug/1681439/+subscriptions