[Bug 1878255] Re: Assertion failure in bdrv_aio_cancel, through ide

["Philippe Mathieu-Daudé" <1878255@bugs.launchpad.net>]

(gdb) fr 4
#4  0x000056378b63e3aa in ide_reset (s=0x56378d64d730) at hw/ide/core.c:1318
1318            blk_aio_cancel(s->pio_aiocb);
(gdb) p *s->pio_aiocb
$1 = {aiocb_info = 0x56378bb55520 <blk_aio_em_aiocb_info>, bs = 0x0, cb = 0x56378b63d9f8 <ide_flush_cb>, opaque = 0x56378d64d730, refcnt = 2}

void bdrv_aio_cancel(BlockAIOCB *acb)
{
    qemu_aio_ref(acb);
    bdrv_aio_cancel_async(acb);
    while (acb->refcnt > 1) {
        if (acb->aiocb_info->get_aio_context) {
            ...
        } else if (acb->bs) {
            ...
        } else {
            abort();
        }

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https://bugs.launchpad.net/bugs/1878255

Title:
  Assertion failure in bdrv_aio_cancel, through ide

Status in QEMU:
  New

Bug description:
  Hello,
  While fuzzing, I found an input that triggers an assertion failure in bdrv_aio_cancel, through ide:

  #1  0x00007ffff685755b in __GI_abort () at abort.c:79
  #2  0x0000555556a8d396 in bdrv_aio_cancel (acb=0x607000061290) at /home/alxndr/Development/qemu/block/io.c:2746
  #3  0x0000555556a58525 in blk_aio_cancel (acb=0x2) at /home/alxndr/Development/qemu/block/block-backend.c:1540
  #4  0x0000555556552f5b in ide_reset (s=<optimized out>) at /home/alxndr/Development/qemu/hw/ide/core.c:1318
  #5  0x0000555556552aeb in ide_bus_reset (bus=0x62d000017398) at /home/alxndr/Development/qemu/hw/ide/core.c:2422
  #6  0x0000555556579ba5 in ahci_reset_port (s=<optimized out>, port=<optimized out>) at /home/alxndr/Development/qemu/hw/ide/ahci.c:650
  #7  0x000055555657bd8d in ahci_port_write (s=0x61e000014d70, port=0x2, offset=<optimized out>, val=0x10) at /home/alxndr/Development/qemu/hw/ide/ahci.c:360
  #8  0x000055555657bd8d in ahci_mem_write (opaque=<optimized out>, addr=<optimized out>, val=<optimized out>, size=<optimized out>) at /home/alxndr/Development/qemu/hw/ide/ahci.c:513
  #9  0x00005555560028d7 in memory_region_write_accessor (mr=<optimized out>, addr=<optimized out>, value=<optimized out>, size=<optimized out>, shift=<optimized out>, mask=<optimized out>, attrs=...) at /home/alxndr/Development/qemu/memory.c:483
  #10 0x0000555556002280 in access_with_adjusted_size (addr=<optimized out>, value=<optimized out>, size=<optimized out>, access_size_min=<optimized out>, access_size_max=<optimized out>, access_fn=<optimized out>, mr=0x61e000014da0, attrs=...) at /home/alxndr/Development/qemu/memory.c:544
  #11 0x0000555556002280 in memory_region_dispatch_write (mr=<optimized out>, addr=<optimized out>, data=0x10, op=<optimized out>, attrs=...) at /home/alxndr/Development/qemu/memory.c:1476
  #12 0x0000555555f171d4 in flatview_write_continue (fv=<optimized out>, addr=0xe106c22c, attrs=..., ptr=<optimized out>, len=0x1, addr1=0x7fffffffb8d0, l=<optimized out>, mr=0x61e000014da0) at /home/alxndr/Development/qemu/exec.c:3137
  #13 0x0000555555f0fb98 in flatview_write (fv=0x60600003b180, addr=<optimized out>, attrs=..., buf=<optimized out>, len=<optimized out>) at /home/alxndr/Development/qemu/exec.c:3177

  I can reproduce it in qemu 5.0 using:

  cat << EOF | ~/Development/qemu/build/i386-softmmu/qemu-system-i386 -qtest stdio -monitor none -serial none -M pc-q35-5.0  -nographic
  outl 0xcf8 0x8000fa24
  outl 0xcfc 0xe106c000
  outl 0xcf8 0x8000fa04
  outw 0xcfc 0x7
  outl 0xcf8 0x8000fb20
  write 0x0 0x3 0x2780e7
  write 0xe106c22c 0xd 0x1130c218021130c218021130c2
  write 0xe106c218 0x15 0x110010110010110010110010110010110010110010
  EOF

  I also attached the commands to this launchpad report, in case the
  formatting is broken:

  qemu-system-i386 -qtest stdio -monitor none -serial none -M pc-q35-5.0
  -nographic < attachment

  Please let me know if I can provide any further info.
  -Alex

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