xemu/tests/qemu-iotests/060
Max Reitz d470ad42ac block: Guard against NULL bs->drv
We currently do not guard everywhere against a NULL bs->drv where we
should be doing so.  Most of the places fixed here just do not care
about that case at all.

Some care implicitly, e.g. through a prior function call to
bdrv_getlength() which would always fail for an ejected BDS.  Add an
assert there to make it more obvious.

Other places seem to care, but do so insufficiently: Freeing clusters in
a qcow2 image is an error-free operation, but it may leave the image in
an unusable state anyway.  Giving qcow2_free_clusters() an error code is
not really viable, it is much easier to note that bs->drv may be NULL
even after a successful driver call.  This concerns bdrv_co_flush(), and
the way the check is added to bdrv_co_pdiscard() (in every iteration
instead of only once).

Finally, some places employ at least an assert(bs->drv); somewhere, that
may be reasonable (such as in the reopen code), but in
bdrv_has_zero_init(), it is definitely not.  Returning 0 there in case
of an ejected BDS saves us much headache instead.

Reported-by: R. Nageswara Sastry <nasastry@in.ibm.com>
Buglink: https://bugs.launchpad.net/qemu/+bug/1728660
Signed-off-by: Max Reitz <mreitz@redhat.com>
Message-id: 20171110203111.7666-4-mreitz@redhat.com
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>
2017-11-17 18:21:31 +01:00

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#!/bin/bash
#
# Test case for image corruption (overlapping data structures) in qcow2
#
# Copyright (C) 2013 Red Hat, Inc.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <http://www.gnu.org/licenses/>.
#
# creator
owner=mreitz@redhat.com
seq="$(basename $0)"
echo "QA output created by $seq"
here="$PWD"
status=1 # failure is the default!
_cleanup()
{
_cleanup_test_img
}
trap "_cleanup; exit \$status" 0 1 2 3 15
# get standard environment, filters and checks
. ./common.rc
. ./common.filter
# This tests qocw2-specific low-level functionality
_supported_fmt qcow2
_supported_proto file
_supported_os Linux
rt_offset=65536 # 0x10000 (XXX: just an assumption)
rb_offset=131072 # 0x20000 (XXX: just an assumption)
l1_offset=196608 # 0x30000 (XXX: just an assumption)
l2_offset=262144 # 0x40000 (XXX: just an assumption)
l2_offset_after_snapshot=524288 # 0x80000 (XXX: just an assumption)
IMGOPTS="compat=1.1"
OPEN_RW="open -o overlap-check=all $TEST_IMG"
# Overlap checks are done before write operations only, therefore opening an
# image read-only makes the overlap-check option irrelevant
OPEN_RO="open -r $TEST_IMG"
echo
echo "=== Testing L2 reference into L1 ==="
echo
_make_test_img 64M
# Link first L1 entry (first L2 table) onto itself
# (Note the MSb in the L1 entry is set, ensuring the refcount is one - else any
# later write will result in a COW operation, effectively ruining this attempt
# on image corruption)
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x03\x00\x00"
_check_test_img
# The corrupt bit should not be set anyway
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
# Try to write something, thereby forcing the corrupt bit to be set
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io
# The corrupt bit must now be set
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
# This information should be available through qemu-img info
_img_info --format-specific
# Try to open the image R/W (which should fail)
$QEMU_IO -c "$OPEN_RW" -c "read 0 512" 2>&1 | _filter_qemu_io \
| _filter_testdir \
| _filter_imgfmt
# Try to open it RO (which should succeed)
$QEMU_IO -c "$OPEN_RO" -c "read 0 512" | _filter_qemu_io
# We could now try to fix the image, but this would probably fail (how should an
# L2 table linked onto the L1 table be fixed?)
echo
echo "=== Testing cluster data reference into refcount block ==="
echo
_make_test_img 64M
# Allocate L2 table
truncate -s "$(($l2_offset+65536))" "$TEST_IMG"
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x04\x00\x00"
# Mark cluster as used
poke_file "$TEST_IMG" "$(($rb_offset+8))" "\x00\x01"
# Redirect new data cluster onto refcount block
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x02\x00\x00"
_check_test_img
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
# Try to fix it
_check_test_img -r all
# The corrupt bit should be cleared
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
# Look if it's really really fixed
$QEMU_IO -c "$OPEN_RW" -c "write -P 0x2a 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
echo
echo "=== Testing cluster data reference into inactive L2 table ==="
echo
_make_test_img 64M
$QEMU_IO -c "$OPEN_RW" -c "write -P 1 0 512" | _filter_qemu_io
$QEMU_IMG snapshot -c foo "$TEST_IMG"
$QEMU_IO -c "$OPEN_RW" -c "write -P 2 0 512" | _filter_qemu_io
# The inactive L2 table remains at its old offset
poke_file "$TEST_IMG" "$l2_offset_after_snapshot" \
"\x80\x00\x00\x00\x00\x04\x00\x00"
_check_test_img
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 3 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
_check_test_img -r all
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
$QEMU_IO -c "$OPEN_RW" -c "write -P 4 0 512" | _filter_qemu_io
$PYTHON qcow2.py "$TEST_IMG" dump-header | grep incompatible_features
# Check data
$QEMU_IO -c "$OPEN_RO" -c "read -P 4 0 512" | _filter_qemu_io
$QEMU_IMG snapshot -a foo "$TEST_IMG"
_check_test_img
$QEMU_IO -c "$OPEN_RO" -c "read -P 1 0 512" | _filter_qemu_io
echo
echo "=== Testing overlap while COW is in flight ==="
echo
# compat=0.10 is required in order to make the following discard actually
# unallocate the sector rather than make it a zero sector - we want COW, after
# all.
IMGOPTS='compat=0.10' _make_test_img 1G
# Write two clusters, the second one enforces creation of an L2 table after
# the first data cluster.
$QEMU_IO -c 'write 0k 64k' -c 'write 512M 64k' "$TEST_IMG" | _filter_qemu_io
# Discard the first cluster. This cluster will soon enough be reallocated and
# used for COW.
$QEMU_IO -c 'discard 0k 64k' "$TEST_IMG" | _filter_qemu_io
# Now, corrupt the image by marking the second L2 table cluster as free.
poke_file "$TEST_IMG" '131084' "\x00\x00" # 0x2000c
# Start a write operation requiring COW on the image stopping it right before
# doing the read; then, trigger the corruption prevention by writing anything to
# any unallocated cluster, leading to an attempt to overwrite the second L2
# table. Finally, resume the COW write and see it fail (but not crash).
echo "open -o file.driver=blkdebug $TEST_IMG
break cow_read 0
aio_write 0k 1k
wait_break 0
write 64k 64k
resume 0" | $QEMU_IO | _filter_qemu_io
echo
echo "=== Testing unallocated image header ==="
echo
_make_test_img 64M
# Create L1/L2
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$rb_offset" "\x00\x00"
$QEMU_IO -c "write 64k 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing unaligned L1 entry ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
# This will be masked with ~(512 - 1) = ~0x1ff, so whether the lower 9 bits are
# aligned or not does not matter
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x04\x2a\x00"
$QEMU_IO -c "read 0 64k" "$TEST_IMG" | _filter_qemu_io
# Test how well zero cluster expansion can cope with this
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l1_offset" "\x80\x00\x00\x00\x00\x04\x2a\x00"
$QEMU_IMG amend -o compat=0.10 "$TEST_IMG"
echo
echo "=== Testing unaligned L2 entry ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x05\x2a\x00"
$QEMU_IO -c "read 0 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing unaligned pre-allocated zero cluster ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x05\x2a\x01"
# zero cluster expansion
$QEMU_IMG amend -o compat=0.10 "$TEST_IMG"
echo
echo "=== Testing unaligned reftable entry ==="
echo
_make_test_img 64M
poke_file "$TEST_IMG" "$rt_offset" "\x00\x00\x00\x00\x00\x02\x2a\x00"
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing non-fatal corruption on freeing ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x05\x2a\x00"
$QEMU_IO -c "discard 0 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing read-only corruption report ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x05\x2a\x00"
# Should only emit a single error message
$QEMU_IO -c "$OPEN_RO" -c "read 0 64k" -c "read 0 64k" | _filter_qemu_io
echo
echo "=== Testing non-fatal and then fatal corruption report ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 128k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x05\x2a\x00"
poke_file "$TEST_IMG" "$(($l2_offset+8))" "\x80\x00\x00\x00\x00\x06\x2a\x00"
# Should emit two error messages
$QEMU_IO -c "discard 0 64k" -c "read 64k 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing empty refcount table ==="
echo
_make_test_img 64M
poke_file "$TEST_IMG" "$rt_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
# Repair the image
_check_test_img -r all
echo
echo "=== Testing empty refcount table with valid L1 and L2 tables ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$rt_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
# Since the first data cluster is already allocated this triggers an
# allocation with an explicit offset (using qcow2_alloc_clusters_at())
# causing a refcount block to be allocated at offset 0
$QEMU_IO -c "write 0 128k" "$TEST_IMG" | _filter_qemu_io
# Repair the image
_check_test_img -r all
echo
echo "=== Testing empty refcount block ==="
echo
_make_test_img 64M
poke_file "$TEST_IMG" "$rb_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
# Repair the image
_check_test_img -r all
echo
echo "=== Testing empty refcount block with compressed write ==="
echo
_make_test_img 64M
$QEMU_IO -c "write 64k 64k" "$TEST_IMG" | _filter_qemu_io
poke_file "$TEST_IMG" "$rb_offset" "\x00\x00\x00\x00\x00\x00\x00\x00"
# The previous write already allocated an L2 table, so now this new
# write will try to allocate a compressed data cluster at offset 0.
$QEMU_IO -c "write -c 0k 64k" "$TEST_IMG" | _filter_qemu_io
# Repair the image
_check_test_img -r all
echo
echo "=== Testing zero refcount table size ==="
echo
_make_test_img 64M
poke_file "$TEST_IMG" "56" "\x00\x00\x00\x00"
$QEMU_IO -c "write 0 64k" "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt
# Repair the image
_check_test_img -r all
echo
echo "=== Testing incorrect refcount table offset ==="
echo
_make_test_img 64M
poke_file "$TEST_IMG" "48" "\x00\x00\x00\x00\x00\x00\x00\x00"
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
echo
echo "=== Testing dirty corrupt image ==="
echo
_make_test_img 64M
# Let the refblock appear unaligned
poke_file "$TEST_IMG" "$rt_offset" "\x00\x00\x00\x00\xff\xff\x2a\x00"
# Mark the image dirty, thus forcing an automatic check when opening it
poke_file "$TEST_IMG" 72 "\x00\x00\x00\x00\x00\x00\x00\x01"
# Open the image (qemu should refuse to do so)
$QEMU_IO -c close "$TEST_IMG" 2>&1 | _filter_testdir | _filter_imgfmt
echo '--- Repairing ---'
# The actual repair should have happened (because of the dirty bit),
# but some cleanup may have failed (like freeing the old reftable)
# because the image was already marked corrupt by that point
_check_test_img -r all
echo
echo "=== Writing to an unaligned preallocated zero cluster ==="
echo
_make_test_img 64M
# Allocate the L2 table
$QEMU_IO -c "write 0 64k" -c "discard 0 64k" "$TEST_IMG" | _filter_qemu_io
# Pretend there is a preallocated zero cluster somewhere inside the
# image header
poke_file "$TEST_IMG" "$l2_offset" "\x80\x00\x00\x00\x00\x00\x2a\x01"
# Let's write to it!
$QEMU_IO -c "write 0 64k" "$TEST_IMG" | _filter_qemu_io
# Can't repair this yet (TODO: We can just deallocate the cluster)
echo
echo '=== Discarding with an unaligned refblock ==='
echo
_make_test_img 64M
$QEMU_IO -c "write 0 128k" "$TEST_IMG" | _filter_qemu_io
# Make our refblock unaligned
poke_file "$TEST_IMG" "$(($rt_offset))" "\x00\x00\x00\x00\x00\x00\x2a\x00"
# Now try to discard something that will be submitted as two requests
# (main part + tail)
$QEMU_IO -c "discard 0 65537" "$TEST_IMG"
echo '--- Repairing ---'
# Fails the first repair because the corruption prevents the check
# function from double-checking
# (Using -q for the first invocation, because otherwise the
# double-check error message appears above the summary for some
# reason -- so let's just hide the summary)
_check_test_img -q -r all
_check_test_img -r all
# success, all done
echo "*** done"
rm -f $seq.full
status=0