qemu-io fails with Assertion `*host_offset != 0' failed

[R.Nageswara Sastry]

git is at HEAD a93ece47fd9edbd4558db24300056c9a57d3bcd4
This is on ppc64le architecture.

Re-production steps:

1. Copy the attached files named test.img to a directory
2. And customize the following command to point to the above directory and run the same.
# cp test.img copy.img
# qemu-io <path to>/copy.img -c "write 884736 34816"

from gdb:
(gdb) bt
#0 0x00003fffad63eff0 in raise () from /lib64/libc.so.6
#1 0x00003fffad64136c in abort () from /lib64/libc.so.6
#2 0x00003fffad634c44 in __assert_fail_base () from /lib64/libc.so.6
#3 0x00003fffad634d34 in __assert_fail () from /lib64/libc.so.6
#4 0x000000001006426c in qcow2_alloc_cluster_offset (bs=0x391e9ad0, offset=884736, bytes=0x3fffaa89fb4c, host_offset=0x3fffaa89fb58, m=0x3fffaa89fb60)
    at block/qcow2-cluster.c:1524
#5 0x000000001004d3f4 in qcow2_co_pwritev (bs=0x391e9ad0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=0) at block/qcow2.c:1919
#6 0x00000000100a9648 in bdrv_driver_pwritev (bs=0x391e9ad0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=16) at block/io.c:898
#7 0x00000000100ab630 in bdrv_aligned_pwritev (child=0x391f51a0, req=0x3fffaa89fdd8, offset=884736, bytes=34816, align=1, qiov=0x3fffce0e2940, flags=16)
    at block/io.c:1440
#8 0x00000000100ac4ac in bdrv_co_pwritev (child=0x391f51a0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=BDRV_REQ_FUA) at block/io.c:1691
#9 0x000000001008da0c in blk_co_pwritev (blk=0x391d9410, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=BDRV_REQ_FUA) at block/block-backend.c:1085
#10 0x000000001008db68 in blk_write_entry (opaque=0x3fffce0e2958) at block/block-backend.c:1110
#11 0x00000000101aa444 in coroutine_trampoline (i0=958427472, i1=0) at util/coroutine-ucontext.c:79
#12 0x00003fffad652b9c in makecontext () from /lib64/libc.so.6
#13 0x0000000000000000 in ?? ()
(gdb) bt full
#0 0x00003fffad63eff0 in raise () from /lib64/libc.so.6
No symbol table info available.
#1 0x00003fffad64136c in abort () from /lib64/libc.so.6
No symbol table info available.
#2 0x00003fffad634c44 in __assert_fail_base () from /lib64/libc.so.6
No symbol table info available.
#3 0x00003fffad634d34 in __assert_fail () from /lib64/libc.so.6
No symbol table info available.
#4 0x000000001006426c in qcow2_alloc_cluster_offset (bs=0x391e9ad0, offset=884736, bytes=0x3fffaa89fb4c, host_offset=0x3fffaa89fb58, m=0x3fffaa89fb60)
    at block/qcow2-cluster.c:1524
        s = 0x391f5d80
        start = 919552
        remaining = 0
        cluster_offset = 399360
        cur_bytes = 34816
        ret = 1
        __PRETTY_FUNCTION__ = "qcow2_alloc_cluster_offset"
#5 0x000000001004d3f4 in qcow2_co_pwritev (bs=0x391e9ad0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=0) at block/qcow2.c:1919
        s = 0x391f5d80
        offset_in_cluster = 360448
        ret = 0
        cur_bytes = 34816
        cluster_offset = 0
        hd_qiov = {iov = 0x391b85a0, niov = 0, nalloc = 1, size = 0}
        bytes_done = 0
        cluster_data = 0x0
        l2meta = 0x392074c0
        __PRETTY_FUNCTION__ = "qcow2_co_pwritev"
#6 0x00000000100a9648 in bdrv_driver_pwritev (bs=0x391e9ad0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=16) at block/io.c:898
        drv = 0x102036f0 <bdrv_qcow2>
        sector_num = 958319760
        nb_sectors = 2340082071
        ret = 743104256
        __PRETTY_FUNCTION__ = "bdrv_driver_pwritev"
#7 0x00000000100ab630 in bdrv_aligned_pwritev (child=0x391f51a0, req=0x3fffaa89fdd8, offset=884736, bytes=34816, align=1, qiov=0x3fffce0e2940, flags=16)
    at block/io.c:1440
        bs = 0x391e9ad0
        drv = 0x102036f0 <bdrv_qcow2>
        waited = false
        ret = 0
        end_sector = 1796
        bytes_remaining = 34816
        max_transfer = 2147483647
        __PRETTY_FUNCTION__ = "bdrv_aligned_pwritev"
#8 0x00000000100ac4ac in bdrv_co_pwritev (child=0x391f51a0, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=BDRV_REQ_FUA) at block/io.c:1691
        bs = 0x391e9ad0
        req = {bs = 0x391e9ad0, offset = 884736, bytes = 34816, type = BDRV_TRACKED_WRITE, serialising = false, overlap_offset = 884736,
          overlap_bytes = 34816, list = {le_next = 0x0, le_prev = 0x391ecd48}, co = 0x39207150, wait_queue = {entries = {sqh_first = 0x0,
              sqh_last = 0x3fffaa89fe20}}, waiting_for = 0x0}
        align = 1
---Type <return> to continue, or q <return> to quit---
        head_buf = 0x0
        tail_buf = 0x0
        local_qiov = {iov = 0x3fffaa89fdb0, niov = -1433797136, nalloc = 16383, size = 884736}
        use_local_qiov = false
        ret = 0
        __PRETTY_FUNCTION__ = "bdrv_co_pwritev"
#9 0x000000001008da0c in blk_co_pwritev (blk=0x391d9410, offset=884736, bytes=34816, qiov=0x3fffce0e2940, flags=BDRV_REQ_FUA) at block/block-backend.c:1085
        ret = 0
        bs = 0x391e9ad0
#10 0x000000001008db68 in blk_write_entry (opaque=0x3fffce0e2958) at block/block-backend.c:1110
        rwco = 0x3fffce0e2958
#11 0x00000000101aa444 in coroutine_trampoline (i0=958427472, i1=0) at util/coroutine-ucontext.c:79
        arg = {p = 0x39207150, i = {958427472, 0}}
        self = 0x39207150
        co = 0x39207150
#12 0x00003fffad652b9c in makecontext () from /lib64/libc.so.6
No symbol table info available.
#13 0x0000000000000000 in ?? ()
No symbol table info available.

Will be attaching image_fuzzer images.

[Max Reitz (xanclic)]

Hi,

Once more, thanks a lot for reporting this bug! I've found a fix and I'll send a patch once I've written a test case.

Max

[Thomas Huth (th-huth)]

Fix has been released with QEMU 2.11:
https://git.qemu.org/?p=qemu.git;a=commitdiff;h=93bbaf03ff7fd490e82