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vnc: rework VncState release workflow. 

Split socket closing and releasing of VncState into two steps.  First
close the socket and set the variable to -1 to indicate shutdown in
progress.  Do the actual release in a few places where we can be sure it
doesn't cause trouble in form of use-after-free.  Add some checks for a
valid socket handle to make sure we don't try to use the closed socket.

Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
This commit is contained in:
Gerd Hoffmann 2009-06-16 14:19:48 +02:00 committed by Anthony Liguori
parent 11a1feb655
commit 198a0039c5
1 changed files with 75 additions and 45 deletions
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120
vnc.c
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@ -216,6 +216,8 @@ static inline uint32_t vnc_has_feature(VncState *vs, int feature) {
*/
static void vnc_update_client(void *opaque);
static void vnc_disconnect_start(VncState *vs);
static void vnc_disconnect_finish(VncState *vs);
static void vnc_colordepth(VncState *vs);
@ -652,9 +654,6 @@ static void send_framebuffer_update(VncState *vs, int x, int y, int w, int h)
static void vnc_copy(VncState *vs, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
{
vs->force_update = 1;
vnc_update_client(vs);
vnc_write_u8(vs, 0); /* msg id */
vnc_write_u8(vs, 0);
vnc_write_u16(vs, 1); /* number of rects */
@ -667,13 +666,22 @@ static void vnc_copy(VncState *vs, int src_x, int src_y, int dst_x, int dst_y, i
static void vnc_dpy_copy(DisplayState *ds, int src_x, int src_y, int dst_x, int dst_y, int w, int h)
{
VncDisplay *vd = ds->opaque;
VncState *vs = vd->clients;
while (vs != NULL) {
VncState *vs, *vn;
for (vs = vd->clients; vs != NULL; vs = vn) {
vn = vs->next;
if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT)) {
vs->force_update = 1;
vnc_update_client(vs);
/* vs might be free()ed here */
}
}
for (vs = vd->clients; vs != NULL; vs = vs->next) {
if (vnc_has_feature(vs, VNC_FEATURE_COPYRECT))
vnc_copy(vs, src_x, src_y, dst_x, dst_y, w, h);
else /* TODO */
vnc_update(vs, dst_x, dst_y, w, h);
vs = vs->next;
}
}
@ -798,6 +806,8 @@ static void vnc_update_client(void *opaque)
if (vs->csock != -1) {
qemu_mod_timer(vs->timer, qemu_get_clock(rt_clock) + VNC_REFRESH_INTERVAL);
} else {
vnc_disconnect_finish(vs);
}
}
@ -868,6 +878,48 @@ static void audio_del(VncState *vs)
}
}
static void vnc_disconnect_start(VncState *vs)
{
if (vs->csock == -1)
return;
qemu_set_fd_handler2(vs->csock, NULL, NULL, NULL, NULL);
closesocket(vs->csock);
vs->csock = -1;
}
static void vnc_disconnect_finish(VncState *vs)
{
qemu_del_timer(vs->timer);
qemu_free_timer(vs->timer);
if (vs->input.buffer) qemu_free(vs->input.buffer);
if (vs->output.buffer) qemu_free(vs->output.buffer);
#ifdef CONFIG_VNC_TLS
vnc_tls_client_cleanup(vs);
#endif /* CONFIG_VNC_TLS */
#ifdef CONFIG_VNC_SASL
vnc_sasl_client_cleanup(vs);
#endif /* CONFIG_VNC_SASL */
audio_del(vs);
VncState *p, *parent = NULL;
for (p = vs->vd->clients; p != NULL; p = p->next) {
if (p == vs) {
if (parent)
parent->next = p->next;
else
vs->vd->clients = p->next;
break;
}
parent = p;
}
if (!vs->vd->clients)
dcl->idle = 1;
qemu_free(vs->server.ds->data);
qemu_free(vs->server.ds);
qemu_free(vs->guest.ds);
qemu_free(vs);
}
int vnc_client_io_error(VncState *vs, int ret, int last_errno)
{
@ -885,39 +937,9 @@ int vnc_client_io_error(VncState *vs, int ret, int last_errno)
}
}
VNC_DEBUG("Closing down client sock %d %d\n", ret, ret < 0 ? last_errno : 0);
qemu_set_fd_handler2(vs->csock, NULL, NULL, NULL, NULL);
closesocket(vs->csock);
qemu_del_timer(vs->timer);
qemu_free_timer(vs->timer);
if (vs->input.buffer) qemu_free(vs->input.buffer);
if (vs->output.buffer) qemu_free(vs->output.buffer);
#ifdef CONFIG_VNC_TLS
vnc_tls_client_cleanup(vs);
#endif /* CONFIG_VNC_TLS */
#ifdef CONFIG_VNC_SASL
vnc_sasl_client_cleanup(vs);
#endif /* CONFIG_VNC_SASL */
audio_del(vs);
VncState *p, *parent = NULL;
for (p = vs->vd->clients; p != NULL; p = p->next) {
if (p == vs) {
if (parent)
parent->next = p->next;
else
vs->vd->clients = p->next;
break;
}
parent = p;
}
if (!vs->vd->clients)
dcl->idle = 1;
qemu_free(vs->server.ds->data);
qemu_free(vs->server.ds);
qemu_free(vs->guest.ds);
qemu_free(vs);
VNC_DEBUG("Closing down client sock: ret %d, errno %d\n",
ret, ret < 0 ? last_errno : 0);
vnc_disconnect_start(vs);
return 0;
}
@ -927,7 +949,8 @@ int vnc_client_io_error(VncState *vs, int ret, int last_errno)
void vnc_client_error(VncState *vs)
{
vnc_client_io_error(vs, -1, EINVAL);
VNC_DEBUG("Closing down client sock: protocol error\n");
vnc_disconnect_start(vs);
}
@ -1110,16 +1133,21 @@ void vnc_client_read(void *opaque)
else
#endif /* CONFIG_VNC_SASL */
ret = vnc_client_read_plain(vs);
if (!ret)
if (!ret) {
if (vs->csock == -1)
vnc_disconnect_finish(vs);
return;
}
while (vs->read_handler && vs->input.offset >= vs->read_handler_expect) {
size_t len = vs->read_handler_expect;
int ret;
ret = vs->read_handler(vs, vs->input.buffer, len);
if (vs->csock == -1)
if (vs->csock == -1) {
vnc_disconnect_finish(vs);
return;
}
if (!ret) {
memmove(vs->input.buffer, vs->input.buffer + len, (vs->input.offset - len));
@ -1134,7 +1162,7 @@ void vnc_write(VncState *vs, const void *data, size_t len)
{
buffer_reserve(&vs->output, len);
if (buffer_empty(&vs->output)) {
if (vs->csock != -1 && buffer_empty(&vs->output)) {
qemu_set_fd_handler2(vs->csock, NULL, vnc_client_read, vnc_client_write, vs);
}
@ -1175,7 +1203,7 @@ void vnc_write_u8(VncState *vs, uint8_t value)
void vnc_flush(VncState *vs)
{
if (vs->output.offset)
if (vs->csock != -1 && vs->output.offset)
vnc_client_write(vs);
}
@ -2009,11 +2037,13 @@ static void vnc_connect(VncDisplay *vd, int csock)
vnc_write(vs, "RFB 003.008\n", 12);
vnc_flush(vs);
vnc_read_when(vs, protocol_version, 12);
vnc_update_client(vs);
reset_keys(vs);
vs->next = vd->clients;
vd->clients = vs;
vnc_update_client(vs);
/* vs might be free()ed here */
}
static void vnc_listen_read(void *opaque)