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1423c170b9
The IOWatchPoll holds a reference to the iochannel while the "child"
source (iwp->src) is removed from the context and freed. Freeing the
source leads to the iochannel being also freed at
qio_channel_fd_source_finalize().
Later, io_watch_poll_prepare() tries to create another source with the
same iochannel and hits an use after free:
==8241==ERROR: AddressSanitizer: heap-use-after-free on address 0x514000000040
READ of size 8 at 0x514000000040 thread T2
#0 0x561c2d272fcd in object_get_class ../qom/object.c:1043:17
#1 0x561c2d338f84 in QIO_CHANNEL_GET_CLASS include/io/channel.h:29:1
#2 0x561c2d33b26f in qio_channel_create_watch ../io/channel.c:388:30
#3 0x561c2d2f0993 in io_watch_poll_prepare ../chardev/char-io.c:65:20
...
0x514000000040 is located 0 bytes inside of 392-byte region [0x514000000040,0x5140000001c8)
freed by thread T2 here:
#0 0x561c2d2319a5 in free
#1 0x7fb2c0926638 in g_free
#2 0x561c2d276507 in object_finalize ../qom/object.c:734:9
#3 0x561c2d271d0d in object_unref ../qom/object.c:1231:9
#4 0x561c2d32ef1d in qio_channel_fd_source_finalize ../io/channel-watch.c:95:5
#5 0x7fb2c091d124 in g_source_unref_internal ../glib/gmain.c:2298
#6 0x561c2d2f0b6c in io_watch_poll_prepare ../chardev/char-io.c:71:9
...
previously allocated by thread T3 (connect) here:
#0 0x561c2d231c69 in malloc
#1 0x7fb2c0926518 in g_malloc
#2 0x561c2d27246e in object_new_with_type ../qom/object.c:767:15
#3 0x561c2d272530 in object_new ../qom/object.c:789:12
#4 0x561c2d320193 in qio_channel_socket_new ../io/channel-socket.c:64:31
#5 0x561c2d308013 in tcp_chr_connect_client_async ../chardev/char-socket.c:1181:12
#6 0x561c2d3002e7 in qmp_chardev_open_socket_client ../chardev/char-socket.c:1281:9
...
Fix the issue by incrementing the iochannel reference count when the
IOWatchPoll takes a reference and decrementing when it is finalized.
Signed-off-by: Fabiano Rosas <farosas@suse.de>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 20260302092225.4088227-6-peter.maydell@linaro.org
[PMM: rebased]
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>