[Xen-changelog] [qemu-upstream-unstable] char: remove watch callback on chardev detach from frontend

[patchbot@xxxxxxx]

commit 8501da4b93959ccbae4d04a673d0f1c5b72b1a4b
Author:     Amit Shah <amit.shah@xxxxxxxxxx>
AuthorDate: Wed Aug 28 15:24:05 2013 +0530
Commit:     Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
CommitDate: Mon Dec 2 21:18:10 2013 -0600

    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: <qemu-stable@xxxxxxxxxx>
    Reported-by: Sibiao Luo <sluo@xxxxxxxxxx>
    Reviewed-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
    Signed-off-by: Amit Shah <amit.shah@xxxxxxxxxx>
    (cherry picked from commit 386a5a1e0057e220f79c48fe3689e3dfb17f1b09)
    
    Signed-off-by: Michael Roth <mdroth@xxxxxxxxxxxxxxxxxx>
---
 qemu-char.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/qemu-char.c b/qemu-char.c
index fa00517..fc1c23d 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;
     }
--
generated by git-patchbot for /home/xen/git/qemu-upstream-unstable.git

_______________________________________________
Xen-changelog mailing list
Xen-changelog@xxxxxxxxxxxxx
http://lists.xensource.com/xen-changelog