From dd0ab2d849f8a93fe54a29eedb8a536fbc42fe5d Mon Sep 17 00:00:00 2001 From: Amit Shah Date: Tue, 8 Oct 2013 06:13:07 +0200 Subject: [PATCH 08/11] char: remove watch callback on chardev detach from frontend RH-Author: Amit Shah Message-id: <0044db8c12053fd38667200f350132d7a3485cde.1381210228.git.amit.shah@redhat.com> Patchwork-id: 54729 O-Subject: [RHEL7 qemu-kvm PATCH 3/3] char: remove watch callback on chardev detach from frontend Bugzilla: 1007222 RH-Acked-by: Paolo Bonzini RH-Acked-by: Gerd Hoffmann RH-Acked-by: Michael S. Tsirkin 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(+) Signed-off-by: Miroslav Rezanina --- qemu-char.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/qemu-char.c b/qemu-char.c index 8d46f98..2fb876c 100644 --- a/qemu-char.c +++ b/qemu-char.c @@ -195,6 +195,8 @@ 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, @@ -205,6 +207,7 @@ 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; } -- 1.7.1