Upstream: ADC support #18
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amboar
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Oct 21, 2024
Allow overlapping request by removing the assert that made it
impossible. There are only two callers:
1. block_copy_task_create()
It already asserts the very same condition before calling
reqlist_init_req().
2. cbw_snapshot_read_lock()
There is no need to have read requests be non-overlapping in
copy-before-write when used for snapshot-access. In fact, there was no
protection against two callers of cbw_snapshot_read_lock() calling
reqlist_init_req() with overlapping ranges and this could lead to an
assertion failure [1].
In particular, with the reproducer script below [0], two
cbw_co_snapshot_block_status() callers could race, with the second
calling reqlist_init_req() before the first one finishes and removes
its conflicting request.
[0]:
> #!/bin/bash -e
> dd if=/dev/urandom of=/tmp/disk.raw bs=1M count=1024
> ./qemu-img create /tmp/fleecing.raw -f raw 1G
> (
> ./qemu-system-x86_64 --qmp stdio \
> --blockdev raw,node-name=node0,file.driver=file,file.filename=/tmp/disk.raw \
> --blockdev raw,node-name=node1,file.driver=file,file.filename=/tmp/fleecing.raw \
> <<EOF
> {"execute": "qmp_capabilities"}
> {"execute": "blockdev-add", "arguments": { "driver": "copy-before-write", "file": "node0", "target": "node1", "node-name": "node3" } }
> {"execute": "blockdev-add", "arguments": { "driver": "snapshot-access", "file": "node3", "node-name": "snap0" } }
> {"execute": "nbd-server-start", "arguments": {"addr": { "type": "unix", "data": { "path": "/tmp/nbd.socket" } } } }
> {"execute": "block-export-add", "arguments": {"id": "exp0", "node-name": "snap0", "type": "nbd", "name": "exp0"}}
> EOF
> ) &
> sleep 5
> while true; do
> ./qemu-nbd -d /dev/nbd0
> ./qemu-nbd -c /dev/nbd0 nbd:unix:/tmp/nbd.socket:exportname=exp0 -f raw -r
> nbdinfo --map 'nbd+unix:///exp0?socket=/tmp/nbd.socket'
> done
[1]:
> #5 0x000071e5f0088eb2 in __GI___assert_fail (...) at ./assert/assert.c:101
> #6 0x0000615285438017 in reqlist_init_req (...) at ../block/reqlist.c:23
> #7 0x00006152853e2d98 in cbw_snapshot_read_lock (...) at ../block/copy-before-write.c:237
> #8 0x00006152853e3068 in cbw_co_snapshot_block_status (...) at ../block/copy-before-write.c:304
> #9 0x00006152853f4d22 in bdrv_co_snapshot_block_status (...) at ../block/io.c:3726
> #10 0x000061528543a63e in snapshot_access_co_block_status (...) at ../block/snapshot-access.c:48
> #11 0x00006152853f1a0a in bdrv_co_do_block_status (...) at ../block/io.c:2474
> #12 0x00006152853f2016 in bdrv_co_common_block_status_above (...) at ../block/io.c:2652
> #13 0x00006152853f22cf in bdrv_co_block_status_above (...) at ../block/io.c:2732
> #14 0x00006152853d9a86 in blk_co_block_status_above (...) at ../block/block-backend.c:1473
> #15 0x000061528538da6c in blockstatus_to_extents (...) at ../nbd/server.c:2374
> #16 0x000061528538deb1 in nbd_co_send_block_status (...) at ../nbd/server.c:2481
> #17 0x000061528538f424 in nbd_handle_request (...) at ../nbd/server.c:2978
> #18 0x000061528538f906 in nbd_trip (...) at ../nbd/server.c:3121
> #19 0x00006152855a7caf in coroutine_trampoline (...) at ../util/coroutine-ucontext.c:175
Cc: qemu-stable@nongnu.org
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-Id: <20240712140716.517911-1-f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
(cherry picked from commit 6475155)
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
amboar
pushed a commit
that referenced
this issue
Dec 11, 2024
…et_end()
In multifd_mapped_ram_fdset_end() we call qtest_qmp() but forgot
to unref the response QDict we get back, which means it is leaked:
Indirect leak of 4120 byte(s) in 1 object(s) allocated from:
#0 0x55c0c095d318 in __interceptor_calloc (/mnt/nvmedisk/linaro/qemu-from-laptop/qemu/build/asan/tests/qtest/migration-test+0x22f318) (BuildI
d: 07f667506452d6c467dbc06fd95191966d3e91b4)
#1 0x7f186f939c50 in g_malloc0 debian/build/deb/../../../glib/gmem.c:161:13
#2 0x55c0c0ae9b01 in qdict_new qobject/qdict.c:30:13
#3 0x55c0c0afc16c in parse_object qobject/json-parser.c:317:12
#4 0x55c0c0afb90f in parse_value qobject/json-parser.c:545:16
#5 0x55c0c0afb579 in json_parser_parse qobject/json-parser.c:579:14
#6 0x55c0c0afa21d in json_message_process_token qobject/json-streamer.c:92:12
#7 0x55c0c0bca2e5 in json_lexer_feed_char qobject/json-lexer.c:313:13
#8 0x55c0c0bc97ce in json_lexer_feed qobject/json-lexer.c:350:9
#9 0x55c0c0afabbc in json_message_parser_feed qobject/json-streamer.c:121:5
#10 0x55c0c09cbd52 in qmp_fd_receive tests/qtest/libqmp.c:86:9
#11 0x55c0c09be69b in qtest_qmp_receive_dict tests/qtest/libqtest.c:760:12
#12 0x55c0c09bca77 in qtest_qmp_receive tests/qtest/libqtest.c:741:27
#13 0x55c0c09bee9d in qtest_vqmp tests/qtest/libqtest.c:812:12
#14 0x55c0c09bd257 in qtest_qmp tests/qtest/libqtest.c:835:16
#15 0x55c0c0a87747 in multifd_mapped_ram_fdset_end tests/qtest/migration-test.c:2393:12
#16 0x55c0c0a85eb3 in test_file_common tests/qtest/migration-test.c:1978:9
#17 0x55c0c0a746a3 in test_multifd_file_mapped_ram_fdset tests/qtest/migration-test.c:2437:5
#18 0x55c0c0a93237 in migration_test_wrapper tests/qtest/migration-helpers.c:458:5
#19 0x7f186f958aed in test_case_run debian/build/deb/../../../glib/gtestutils.c:2930:15
#20 0x7f186f958aed in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3018:16
#21 0x7f186f95880a in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3035:18
#22 0x7f186f95880a in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3035:18
#23 0x7f186f95880a in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3035:18
#24 0x7f186f95880a in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3035:18
#25 0x7f186f95880a in g_test_run_suite_internal debian/build/deb/../../../glib/gtestutils.c:3035:18
#26 0x7f186f958faa in g_test_run_suite debian/build/deb/../../../glib/gtestutils.c:3109:18
#27 0x7f186f959055 in g_test_run debian/build/deb/../../../glib/gtestutils.c:2231:7
#28 0x7f186f959055 in g_test_run debian/build/deb/../../../glib/gtestutils.c:2218:1
#29 0x55c0c0a6e427 in main tests/qtest/migration-test.c:4033:11
Unref the object after we've confirmed that it is what we expect.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Fabiano Rosas <farosas@suse.de>
Signed-off-by: Fabiano Rosas <farosas@suse.de>
amboar
pushed a commit
that referenced
this issue
Dec 11, 2024
Allow overlapping request by removing the assert that made it
impossible. There are only two callers:
1. block_copy_task_create()
It already asserts the very same condition before calling
reqlist_init_req().
2. cbw_snapshot_read_lock()
There is no need to have read requests be non-overlapping in
copy-before-write when used for snapshot-access. In fact, there was no
protection against two callers of cbw_snapshot_read_lock() calling
reqlist_init_req() with overlapping ranges and this could lead to an
assertion failure [1].
In particular, with the reproducer script below [0], two
cbw_co_snapshot_block_status() callers could race, with the second
calling reqlist_init_req() before the first one finishes and removes
its conflicting request.
[0]:
> #!/bin/bash -e
> dd if=/dev/urandom of=/tmp/disk.raw bs=1M count=1024
> ./qemu-img create /tmp/fleecing.raw -f raw 1G
> (
> ./qemu-system-x86_64 --qmp stdio \
> --blockdev raw,node-name=node0,file.driver=file,file.filename=/tmp/disk.raw \
> --blockdev raw,node-name=node1,file.driver=file,file.filename=/tmp/fleecing.raw \
> <<EOF
> {"execute": "qmp_capabilities"}
> {"execute": "blockdev-add", "arguments": { "driver": "copy-before-write", "file": "node0", "target": "node1", "node-name": "node3" } }
> {"execute": "blockdev-add", "arguments": { "driver": "snapshot-access", "file": "node3", "node-name": "snap0" } }
> {"execute": "nbd-server-start", "arguments": {"addr": { "type": "unix", "data": { "path": "/tmp/nbd.socket" } } } }
> {"execute": "block-export-add", "arguments": {"id": "exp0", "node-name": "snap0", "type": "nbd", "name": "exp0"}}
> EOF
> ) &
> sleep 5
> while true; do
> ./qemu-nbd -d /dev/nbd0
> ./qemu-nbd -c /dev/nbd0 nbd:unix:/tmp/nbd.socket:exportname=exp0 -f raw -r
> nbdinfo --map 'nbd+unix:///exp0?socket=/tmp/nbd.socket'
> done
[1]:
> #5 0x000071e5f0088eb2 in __GI___assert_fail (...) at ./assert/assert.c:101
> #6 0x0000615285438017 in reqlist_init_req (...) at ../block/reqlist.c:23
> #7 0x00006152853e2d98 in cbw_snapshot_read_lock (...) at ../block/copy-before-write.c:237
> #8 0x00006152853e3068 in cbw_co_snapshot_block_status (...) at ../block/copy-before-write.c:304
> #9 0x00006152853f4d22 in bdrv_co_snapshot_block_status (...) at ../block/io.c:3726
> #10 0x000061528543a63e in snapshot_access_co_block_status (...) at ../block/snapshot-access.c:48
> #11 0x00006152853f1a0a in bdrv_co_do_block_status (...) at ../block/io.c:2474
> #12 0x00006152853f2016 in bdrv_co_common_block_status_above (...) at ../block/io.c:2652
> #13 0x00006152853f22cf in bdrv_co_block_status_above (...) at ../block/io.c:2732
> #14 0x00006152853d9a86 in blk_co_block_status_above (...) at ../block/block-backend.c:1473
> #15 0x000061528538da6c in blockstatus_to_extents (...) at ../nbd/server.c:2374
> #16 0x000061528538deb1 in nbd_co_send_block_status (...) at ../nbd/server.c:2481
> #17 0x000061528538f424 in nbd_handle_request (...) at ../nbd/server.c:2978
> #18 0x000061528538f906 in nbd_trip (...) at ../nbd/server.c:3121
> #19 0x00006152855a7caf in coroutine_trampoline (...) at ../util/coroutine-ucontext.c:175
Cc: qemu-stable@nongnu.org
Suggested-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
Message-Id: <20240712140716.517911-1-f.ebner@proxmox.com>
Reviewed-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
Signed-off-by: Vladimir Sementsov-Ogievskiy <vsementsov@yandex-team.ru>
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The ADC support depends on the unaligned access handling patch mentioned in #17. Resolve any outstanding issues on the ADC model and upstream with the patch for #17.
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