If a frontend device releases the chardev (via unplug), the chr handlers are set to NULL via qdev's exit callbacks invoking qemu_chr_add_handlers(). If the chardev had a pending operation, a callback will be invoked, which will try to access data in the just-released frontend, causing a segfault.
Ensure the callbacks are disabled when frontends release chardevs. This was seen when a virtio-serial port was unplugged when heavy guest->host IO was in progress (causing a callback to be registered). In the window in which the throttling was active, unplugging ports caused a qemu segfault. https://bugzilla.redhat.com/show_bug.cgi?id=985205 CC: <qemu-sta...@nongnu.org> Reported-by: Sibiao Luo <s...@redhat.com> Signed-off-by: Amit Shah <amit.s...@redhat.com> --- qemu-char.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index 3dcf322..347fa5e 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -193,6 +193,8 @@ void qemu_chr_fe_printf(CharDriverState *s, const char *fmt, ...) va_end(ap); } +static void remove_fd_in_watch(CharDriverState *chr); + void qemu_chr_add_handlers(CharDriverState *s, IOCanReadHandler *fd_can_read, IOReadHandler *fd_read, @@ -203,6 +205,7 @@ void qemu_chr_add_handlers(CharDriverState *s, if (!opaque && !fd_can_read && !fd_read && !fd_event) { fe_open = 0; + remove_fd_in_watch(s); } else { fe_open = 1; } -- 1.8.3.1
