From: Amit Shah Date: Wed, 28 Aug 2013 09:54:05 +0000 (+0530) Subject: char: remove watch callback on chardev detach from frontend X-Git-Tag: qemu-xen-4.4.0-rc3~40 X-Git-Url: http://xenbits.xensource.com/gitweb?a=commitdiff_plain;h=8501da4b93959ccbae4d04a673d0f1c5b72b1a4b;p=qemu-upstream-4.5-testing.git char: remove watch callback on chardev detach from frontend 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: Reported-by: Sibiao Luo Reviewed-by: Gerd Hoffmann Signed-off-by: Amit Shah (cherry picked from commit 386a5a1e0057e220f79c48fe3689e3dfb17f1b09) Signed-off-by: Michael Roth --- diff --git a/qemu-char.c b/qemu-char.c index fa005174d..fc1c23d2c 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; }