Stefan Hajnoczi 6d740fb01b aio-posix: do not nest poll handlers ... QEMU's event loop supports nesting, which means that event handler functions may themselves call aio_poll(). The condition that triggered a handler must be reset before the nested aio_poll() call, otherwise the same handler will be called and immediately re-enter aio_poll. This leads to an infinite loop and stack exhaustion. Poll handlers are especially prone to this issue, because they typically reset their condition by finishing the processing of pending work. Unfortunately it is during the processing of pending work that nested aio_poll() calls typically occur and the condition has not yet been reset. Disable a poll handler during ->io_poll_ready() so that a nested aio_poll() call cannot invoke ->io_poll_ready() again. As a result, the disabled poll handler and its associated fd handler do not run during the nested aio_poll(). Calling aio_set_fd_handler() from inside nested aio_poll() could cause it to run again. If the fd handler is pending inside nested aio_poll(), then it will also run again. In theory fd handlers can be affected by the same issue, but they are more likely to reset the condition before calling nested aio_poll(). This is a special case and it's somewhat complex, but I don't see a way around it as long as nested aio_poll() is supported. Cc: qemu-stable@nongnu.org Buglink: https://bugzilla.redhat.com/show_bug.cgi?id=2186181 Fixes: c382706925 ("block: Mark bdrv_co_io_(un)plug() and callers GRAPH_RDLOCK") Cc: Kevin Wolf <kwolf@redhat.com> Cc: Emanuele Giuseppe Esposito <eesposit@redhat.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com> Message-Id: <20230502184134.534703-2-stefanha@redhat.com> Reviewed-by: Kevin Wolf <kwolf@redhat.com> Signed-off-by: Kevin Wolf <kwolf@redhat.com>		2023-05-19 19:12:12 +02:00
..
aio-posix.c	aio-posix: do not nest poll handlers	2023-05-19 19:12:12 +02:00
aio-posix.h	aio-posix: fix spurious ->poll_ready() callbacks in main loop	2022-03-17 11:23:18 +00:00
aio-wait.c	aio-wait: avoid AioContext lock in aio_wait_bh_oneshot()	2023-05-10 14:15:13 +02:00
aio-win32.c	win32: avoid mixing SOCKET and file descriptor space	2023-03-13 15:39:31 +04:00
aiocb.c	block: move AioContext, QEMUTimer, main-loop to libqemuutil	2017-02-21 11:14:07 +00:00
async-teardown.c	util/async-teardown: wire up query-command-line-options	2023-05-16 09:14:18 +02:00
async.c	async: avoid use-after-free on re-entrancy guard	2023-05-02 10:03:26 +02:00
atomic64.c	osdep: Move memalign-related functions to their own header	2022-03-07 13:16:49 +00:00
base64.c	nomaintainer: Fix Lesser GPL version number	2020-11-15 17:04:40 +01:00
bitmap.c	migration: Use non-atomic ops for clear log bitmap	2022-11-21 11:58:10 +01:00
bitops.c	replace TABs with spaces	2023-03-20 12:43:50 +01:00
block-helpers.c	block: move logical block size check function to a common utility function	2020-10-23 13:42:16 +01:00
block-helpers.h	block: move logical block size check function to a common utility function	2020-10-23 13:42:16 +01:00
buffer.c	nomaintainer: Fix Lesser GPL version number	2020-11-15 17:04:40 +01:00
bufferiszero.c	include/qemu/cpuid: Introduce xgetbv_low	2023-03-05 13:44:07 -08:00
cacheflush.c	util/cacheflush: fix cache on windows-arm64	2023-02-21 08:53:03 -10:00
compatfd.c	util: replace pipe()+cloexec with g_unix_open_pipe()	2022-05-03 15:18:14 +04:00
coroutine-sigaltstack.c	Remove qemu-common.h include from most units	2022-04-06 14:31:55 +02:00
coroutine-ucontext.c	coroutine-ucontext: use QEMU_DEFINE_STATIC_CO_TLS()	2022-05-04 15:55:23 +02:00
coroutine-windows.c	build: move coroutine backend selection to meson	2023-05-18 08:53:52 +02:00
crc-ccitt.c	util: Add CRC16 (CCITT) calculation routines	2021-01-24 20:10:54 +01:00
crc32c.c	Include qemu-common.h exactly where needed	2019-06-12 13:20:20 +02:00
cutils.c	util: remove support for hex numbers with a scaling suffix	2023-01-06 00:51:02 +01:00
dbus.c	util: add dbus helper unit	2020-01-06 18:41:32 +04:00
drm.c	util/drm: make portable by avoiding struct dirent d_type	2020-07-13 14:36:10 +01:00
envlist.c	replace TABs with spaces	2023-03-20 12:43:50 +01:00
error-report.c	util/error: add G_GNUC_PRINTF for various functions	2023-01-11 10:44:34 +01:00
error.c	util/error: Fix use-after-free errors reported by Coverity	2023-04-06 12:38:42 -04:00
event_notifier-posix.c	Replace qemu_pipe() with g_unix_open_pipe()	2022-05-03 15:17:56 +04:00
event_notifier-win32.c	Remove qemu-common.h include from most units	2022-04-06 14:31:55 +02:00
fdmon-epoll.c	aio-posix: fix race between epoll upgrade and aio_set_fd_handler()	2023-03-27 15:12:17 +02:00
fdmon-io_uring.c	aio-posix: fix build failure io_uring 2.2	2022-03-17 11:23:18 +00:00
fdmon-poll.c	fdmon-poll: reset npfd when upgrading to fdmon-epoll	2020-09-23 13:45:52 +01:00
fifo8.c	utils/fifo8: change fatal errors from abort() to assert()	2021-02-07 20:38:20 +00:00
filemonitor-inotify.c	nomaintainer: Fix Lesser GPL version number	2020-11-15 17:04:40 +01:00
filemonitor-stub.c	nomaintainer: Fix Lesser GPL version number	2020-11-15 17:04:40 +01:00
getauxval.c	util/getauxval: Porting to FreeBSD getauxval feature	2020-06-26 06:45:29 -04:00
guest-random.c	replay: Extract core API to 'exec/replay-core.h'	2023-02-27 22:29:01 +01:00
hbitmap.c	hbitmap: fix hbitmap_status() return value for first dirty bit case	2023-02-17 14:34:24 +01:00
hexdump.c	include: move C/util-related declarations to cutils.h	2022-04-06 14:31:43 +02:00
host-utils.c	host-utils: Implemented signed 256-by-128 division	2022-06-20 08:38:58 -03:00
id.c	net: Use id_generate() in the network subsystem, too	2021-03-09 21:47:45 +01:00
int128.c	include/qemu/int128: Use Int128 structure for TCI	2023-02-04 06:19:42 -10:00
interval-tree.c	util: Add interval-tree.c	2022-12-20 17:09:41 -08:00
iov.c	util: make do_send_recv work with partial send/recv	2022-10-12 19:22:01 +04:00
iova-tree.c	util: accept iova_tree_remove_parameter by value	2022-09-02 10:22:39 +08:00
keyval.c	include: add qemu/keyval.h	2022-04-21 17:03:51 +04:00
lockcnt.c	qemu/atomic.h: rename atomic_ to qatomic_	2020-09-23 16:07:44 +01:00
log.c	log: Remove unneeded new line	2023-03-08 00:37:48 +01:00
main-loop.c	async: Add an optional reentrancy guard to the BH API	2023-04-28 11:31:07 +02:00
memalign.c	osdep: Move memalign-related functions to their own header	2022-03-07 13:16:49 +00:00
memfd.c	linux-user: add memfd_create	2019-09-11 08:46:17 +02:00
meson.build	build: move coroutine backend selection to meson	2023-05-18 08:53:52 +02:00
mmap-alloc.c	util/mmap-alloc: qemu_fd_getfs()	2023-04-24 11:29:00 +02:00
module.c	module: add Error arguments to module_load and module_load_qom	2022-11-06 09:48:50 +01:00
notify.c	xen / notify: introduce a new XenWatchList abstraction	2019-09-24 12:18:47 +01:00
nvdimm-utils.c	Clean up includes	2020-12-10 17:16:44 +01:00
osdep.c	error handling: Use RETRY_ON_EINTR() macro where applicable	2023-01-09 13:50:47 +01:00
oslib-posix.c	util: drop qemu_fork()	2023-03-13 15:23:37 +04:00
oslib-win32.c	win32: add qemu_close_socket_osfhandle()	2023-03-21 11:16:03 +04:00
path.c	util/path: Do not cache all filenames at startup	2019-06-24 22:19:30 +02:00
qdist.c	qdist: return "(empty)" instead of NULL when printing an empty dist	2016-08-03 18:44:56 +02:00
qemu-co-shared-resource.c	co-shared-resource: protect with a mutex	2021-06-25 14:24:24 +03:00
qemu-co-timeout.c	util: add qemu-co-timeout	2022-06-29 10:56:12 +03:00
qemu-config.c	error: Drop superfluous #include "qapi/qmp/qerror.h"	2023-02-23 13:56:14 +01:00
qemu-coroutine-io.c	Remove qemu-common.h include from most units	2022-04-06 14:31:55 +02:00
qemu-coroutine-lock.c	qemu-coroutine-lock: add smp_mb__after_rmw()	2023-03-07 12:39:53 +01:00
qemu-coroutine-sleep.c	coroutine: Clean up superfluous inclusion of qemu/coroutine.h	2023-01-19 10:18:28 +01:00
qemu-coroutine.c	qemu-coroutine: remove qatomic_mb_read()	2023-04-20 11:17:35 +02:00
qemu-option.c	qemu-option: Allow deleting opts during qemu_opts_foreach()	2021-10-15 16:11:22 +02:00
qemu-print.c	monitor: Use getter/setter functions for cur_mon	2020-10-09 07:08:19 +02:00
qemu-progress.c	include: move progress API to qemu-progress.h	2022-04-06 14:31:43 +02:00
qemu-sockets.c	win32: replace closesocket() with close() wrapper	2023-03-13 15:39:31 +04:00
qemu-thread-common.h	Clean up includes	2018-12-20 10:29:08 +01:00
qemu-thread-posix.c	qemu-thread-posix: cleanup, fix, document QemuEvent	2023-03-07 12:38:40 +01:00
qemu-thread-win32.c	qemu-thread-win32: cleanup, fix, document QemuEvent	2023-03-07 12:38:40 +01:00
qemu-timer-common.c	semihosting: Implement SYS_ELAPSED and SYS_TICKFREQ	2021-01-18 10:05:06 +00:00
qemu-timer.c	qemu-timer: Skip empty timer lists before locking in qemu_clock_deadline_ns_all	2022-06-21 09:24:34 -07:00
qht.c	util/qht: use striped locks under TSAN	2023-02-02 11:48:20 +00:00
qsp.c	qemu/atomic: Add aligned_{int64,uint64}_t types	2021-07-21 07:45:38 -10:00
qtree.c	tcg: use QTree instead of GTree	2023-03-28 15:23:10 -07:00
range.c	Don't talk about the LGPL if the file is licensed under the GPL	2019-01-30 10:51:20 +01:00
rcu.c	call_rcu: stop using mb_set/mb_read	2023-05-08 11:10:49 +02:00
readline.c	readline: Extract readline_add_completion_of() from monitor	2023-02-04 07:56:54 +01:00
selfmap.c	util/selfmap: Discard mapping on error	2021-07-26 07:06:49 -10:00
stats64.c	stat64: Add stat64_set() operation	2023-04-27 16:39:43 +02:00
sys_membarrier.c	sys_membarrier: fix up include directives	2018-04-05 14:37:38 +02:00
systemd.c	systemd: Also clear LISTEN_FDNAMES during systemd socket activation	2023-05-03 14:00:08 -05:00
thread-context.c	qapi: Use returned bool to check for failure (again)	2022-12-14 16:19:35 +01:00
thread-pool.c	thread-pool: avoid passing the pool parameter every time	2023-04-25 13:17:28 +02:00
throttle.c	Remove superfluous timer_del() calls	2021-01-08 15:13:38 +00:00
timed-average.c
trace-events	async: Add an optional reentrancy guard to the BH API	2023-04-28 11:31:07 +02:00
trace.h	trace: switch position of headers to what Meson requires	2020-08-21 06:18:24 -04:00
transactions.c	transactions: Invoke clean() after everything else	2021-11-16 09:43:44 +01:00
unicode.c	json: Reject invalid UTF-8 sequences	2018-08-24 20:26:37 +02:00
uri.c	Updated the FSF address to <https://www.gnu.org/licenses/>	2023-02-27 09:15:39 +01:00
userfaultfd.c	util/userfaultfd: Support /dev/userfaultfd	2023-02-11 16:51:09 +01:00
uuid.c	Include qemu-common.h exactly where needed	2019-06-12 13:20:20 +02:00
vfio-helpers.c	error handling: Use RETRY_ON_EINTR() macro where applicable	2023-01-09 13:50:47 +01:00
vhost-user-server.c	block/export: only acquire AioContext once for vhost_user_server_stop()	2023-03-27 13:46:30 +02:00
yank.c	yank: Remove dependency on qiochannel	2021-04-01 15:27:44 +04:00