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openSUSE:Evergreen:11.1:kernel-2.6.32
kvm
kvm-qemu-preXX-use-after-free.patch
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File kvm-qemu-preXX-use-after-free.patch of Package kvm
This patch addresses bnc#547555 - CVE-2009-3616 Taken from: commit 198a0039c5fca224a77e9761e2350dd9cc102ad0 Author: Gerd Hoffmann <kraxel@redhat.com> Date: Tue Jun 16 14:19:48 2009 +0200 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> Signed-off-by: Bruce Rogers <brogers@novell.com> diff --git a/vnc.c b/vnc.c index 1d8ebe7..39c8b0f 100644 --- a/vnc.c +++ b/vnc.c @@ -200,6 +200,8 @@ static void vnc_write_u16(VncState *vs, uint16_t value); static void vnc_write_u8(VncState *vs, uint8_t value); static void vnc_flush(VncState *vs); static void vnc_update_client(void *opaque); +static void vnc_disconnect_start(VncState *vs); +static void vnc_disconnect_finish(VncState *vs); static void vnc_client_read(void *opaque); static void vnc_colordepth(VncState *vs); @@ -633,8 +635,6 @@ 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) { - vnc_update_client(vs); - vnc_write_u8(vs, 0); /* msg id */ vnc_write_u8(vs, 0); vnc_write_u16(vs, 1); /* number of rects */ @@ -647,13 +647,21 @@ 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)) { + 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; } } @@ -763,6 +772,8 @@ 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); } } @@ -848,38 +859,10 @@ static 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 - if (vs->tls_session) { - gnutls_deinit(vs->tls_session); - vs->tls_session = NULL; - } -#endif /* CONFIG_VNC_TLS */ - 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->old_data); - 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; } return ret; @@ -887,7 +870,9 @@ static int vnc_client_io_error(VncState *vs, int ret, int last_errno) static 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); + } static void vnc_client_write(void *opaque) @@ -947,8 +932,11 @@ static void vnc_client_read(void *opaque) #endif /* CONFIG_VNC_TLS */ ret = recv(vs->csock, buffer_end(&vs->input), 4096, 0); ret = vnc_client_io_error(vs, ret, socket_error()); - if (!ret) + if (!ret) { + if (vs->csock == -1) + vnc_disconnect_finish(vs); return; + } vs->input.offset += ret; @@ -957,8 +945,10 @@ static void vnc_client_read(void *opaque) 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)); @@ -973,7 +963,7 @@ static 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); } @@ -1014,7 +1004,7 @@ static void vnc_write_u8(VncState *vs, uint8_t value) static void vnc_flush(VncState *vs) { - if (vs->output.offset) + if (vs->csock != -1 && vs->output.offset) vnc_client_write(vs); } @@ -1057,6 +1047,46 @@ static ssize_t vnc_tls_push(gnutls_transport_ptr_t transport, return ret; } +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 + if (vs->tls_session) { + gnutls_deinit(vs->tls_session); + vs->tls_session = NULL; + } +#endif /* CONFIG_VNC_TLS */ + 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->old_data); + qemu_free(vs); +} static ssize_t vnc_tls_pull(gnutls_transport_ptr_t transport, void *data, @@ -2282,11 +2311,13 @@ static void vnc_connect(VncDisplay *vd, int csock) vnc_read_when(vs, protocol_version, 12); memset(vs->old_data, 0, ds_get_linesize(vs->ds) * ds_get_height(vs->ds)); memset(vs->dirty_row, 0xFF, sizeof(vs->dirty_row)); - 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)
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