From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:54012) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VEf0H-0001Z0-Ko for qemu-devel@nongnu.org; Wed, 28 Aug 2013 08:37:46 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VEf0C-0001Sg-Fl for qemu-devel@nongnu.org; Wed, 28 Aug 2013 08:37:41 -0400 From: Amit Shah Date: Wed, 28 Aug 2013 18:07:22 +0530 Message-Id: <19f7801e0722b3ceb79af02704bcad5c7adab318.1377693391.git.amit.shah@redhat.com> In-Reply-To: References: In-Reply-To: References: Subject: [Qemu-devel] [PATCH v3 3/3] char: remove watch callback on chardev detach from frontend List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu list Cc: qemu-stable@nongnu.org, Hans de Goede , Gerd Hoffmann , Anthony Liguori , Amit Shah , Paolo Bonzini 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 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 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