[Xen-changelog] [xen-unstable] Fix use-after-free in xenconsoled.

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir@xxxxxxxxxxxxx>
# Date 1193934883 0
# Node ID 2462265f09ae310d7c8e8b194ce9e01430cb9071
# Parent  7cd040290f82e66f36685294cff8ca18f64079d9
Fix use-after-free in xenconsoled.

shutdown_domain() MUST NOT call cleanup_domain(), just flagging them
as dead is enough.  cleanup_domains() for dead domains is called by
the main loop in handle_io() in a safe way already.

shutdown_domain() calling cleanup_domain() too leads struct domain
being accessed after freeing and to a double-free.

Fixed by simply dropping the cleanup_domain() call and by making the
functions called by the main loop in handle_io() ignore dead domains.

Signed-off-by: Gerd Hoffmann <kraxel@xxxxxxxxxx>
---
 tools/console/daemon/io.c |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletion(-)

diff -r 7cd040290f82 -r 2462265f09ae tools/console/daemon/io.c
--- a/tools/console/daemon/io.c Thu Nov 01 16:34:20 2007 +0000
+++ b/tools/console/daemon/io.c Thu Nov 01 16:34:43 2007 +0000
@@ -628,7 +628,6 @@ static void shutdown_domain(struct domai
        if (d->xce_handle != -1)
                xc_evtchn_close(d->xce_handle);
        d->xce_handle = -1;
-       cleanup_domain(d);
 }
 
 void enum_domains(void)
@@ -674,6 +673,9 @@ static void handle_tty_read(struct domai
        struct xencons_interface *intf = dom->interface;
        XENCONS_RING_IDX prod;
 
+       if (dom->is_dead)
+               return;
+
        len = ring_free_bytes(dom);
        if (len == 0)
                return;
@@ -711,6 +713,9 @@ static void handle_tty_write(struct doma
 {
        ssize_t len;
 
+       if (dom->is_dead)
+               return;
+
        len = write(dom->tty_fd, dom->buffer.data + dom->buffer.consumed,
                    dom->buffer.size - dom->buffer.consumed);
        if (len < 1) {
@@ -733,6 +738,9 @@ static void handle_ring_read(struct doma
 static void handle_ring_read(struct domain *dom)
 {
        evtchn_port_or_error_t port;
+
+       if (dom->is_dead)
+               return;
 
        if ((port = xc_evtchn_pending(dom->xce_handle)) == -1)
                return;

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