From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:37360) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VHeHk-0007xq-78 for qemu-devel@nongnu.org; Thu, 05 Sep 2013 14:28:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VHeHf-0004hK-7f for qemu-devel@nongnu.org; Thu, 05 Sep 2013 14:28:04 -0400 From: Amit Shah Date: Thu, 5 Sep 2013 23:57:36 +0530 Message-Id: <386a5a1e0057e220f79c48fe3689e3dfb17f1b09.1378386450.git.amit.shah@redhat.com> In-Reply-To: References: In-Reply-To: References: Subject: [Qemu-devel] [PATCH 3/3] char: remove watch callback on chardev detach from frontend List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Amit Shah , Paolo Bonzini , qemu-stable@nongnu.org, qemu list , Gerd Hoffmann 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 --- qemu-char.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/qemu-char.c b/qemu-char.c index 0a0833f..6f111ab 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