diff options
| author | Stefan Hajnoczi <stefanha@redhat.com> | 2020-07-20 11:01:41 +0100 |
|---|---|---|
| committer | Max Reitz <mreitz@redhat.com> | 2020-07-21 12:00:38 +0200 |
| commit | 1d719ddc35e9827b6e5df771555874df34301a0d (patch) | |
| tree | bd83ee01a689418db1beb6d87bd037f69157c606 /block | |
| parent | 0fca43de1b617a95f2472691ca1e740932ab2fea (diff) | |
block: fix bdrv_aio_cancel() for ENOMEDIUM requests
bdrv_aio_cancel() calls aio_poll() on the AioContext for the given I/O
request until it has completed. ENOMEDIUM requests are special because
there is no BlockDriverState when the drive has no medium!
Define a .get_aio_context() function for BlkAioEmAIOCB requests so that
bdrv_aio_cancel() can find the AioContext where the completion BH is
pending. Without this function bdrv_aio_cancel() aborts on ENOMEDIUM
requests!
libFuzzer triggered the following assertion:
cat << EOF | qemu-system-i386 -M pc-q35-5.0 \
-nographic -monitor none -serial none \
-qtest stdio -trace ide\*
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
ide_exec_cmd IDE exec cmd: bus 0x56170a77a2b8; state 0x56170a77a340; cmd 0xe7
ide_reset IDEstate 0x56170a77a340
Aborted (core dumped)
(gdb) bt
#1 0x00007ffff4f93895 in abort () at /lib64/libc.so.6
#2 0x0000555555dc6c00 in bdrv_aio_cancel (acb=0x555556765550) at block/io.c:2745
#3 0x0000555555dac202 in blk_aio_cancel (acb=0x555556765550) at block/block-backend.c:1546
#4 0x0000555555b1bd74 in ide_reset (s=0x555557213340) at hw/ide/core.c:1318
#5 0x0000555555b1e3a1 in ide_bus_reset (bus=0x5555572132b8) at hw/ide/core.c:2422
#6 0x0000555555b2aa27 in ahci_reset_port (s=0x55555720eb50, port=2) at hw/ide/ahci.c:650
#7 0x0000555555b29fd7 in ahci_port_write (s=0x55555720eb50, port=2, offset=44, val=16) at hw/ide/ahci.c:360
#8 0x0000555555b2a564 in ahci_mem_write (opaque=0x55555720eb50, addr=556, val=16, size=1) at hw/ide/ahci.c:513
#9 0x000055555598415b in memory_region_write_accessor (mr=0x55555720eb80, addr=556, value=0x7fffffffb838, size=1, shift=0, mask=255, attrs=...) at softmmu/memory.c:483
Looking at bdrv_aio_cancel:
2728 /* async I/Os */
2729
2730 void bdrv_aio_cancel(BlockAIOCB *acb)
2731 {
2732 qemu_aio_ref(acb);
2733 bdrv_aio_cancel_async(acb);
2734 while (acb->refcnt > 1) {
2735 if (acb->aiocb_info->get_aio_context) {
2736 aio_poll(acb->aiocb_info->get_aio_context(acb), true);
2737 } else if (acb->bs) {
2738 /* qemu_aio_ref and qemu_aio_unref are not thread-safe, so
2739 * assert that we're not using an I/O thread. Thread-safe
2740 * code should use bdrv_aio_cancel_async exclusively.
2741 */
2742 assert(bdrv_get_aio_context(acb->bs) == qemu_get_aio_context());
2743 aio_poll(bdrv_get_aio_context(acb->bs), true);
2744 } else {
2745 abort(); <===============
2746 }
2747 }
2748 qemu_aio_unref(acb);
2749 }
Fixes: 02c50efe08736116048d5fc355043080f4d5859c ("block: Add bdrv_aio_cancel_async")
Reported-by: Alexander Bulekov <alxndr@bu.edu>
Buglink: https://bugs.launchpad.net/qemu/+bug/1878255
Originally-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-Id: <20200720100141.129739-1-stefanha@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
Diffstat (limited to 'block')
| -rw-r--r-- | block/block-backend.c | 8 |
1 files changed, 8 insertions, 0 deletions
diff --git a/block/block-backend.c b/block/block-backend.c index 0bf0188133..3a13cb5f0b 100644 --- a/block/block-backend.c +++ b/block/block-backend.c @@ -1394,8 +1394,16 @@ typedef struct BlkAioEmAIOCB { bool has_returned; } BlkAioEmAIOCB; +static AioContext *blk_aio_em_aiocb_get_aio_context(BlockAIOCB *acb_) +{ + BlkAioEmAIOCB *acb = container_of(acb_, BlkAioEmAIOCB, common); + + return blk_get_aio_context(acb->rwco.blk); +} + static const AIOCBInfo blk_aio_em_aiocb_info = { .aiocb_size = sizeof(BlkAioEmAIOCB), + .get_aio_context = blk_aio_em_aiocb_get_aio_context, }; static void blk_aio_complete(BlkAioEmAIOCB *acb) |