| From 3e246244864c81b2b485628c1f889ba921f2cea3 Mon Sep 17 00:00:00 2001 |
| From: Xin Xiong <xiongx18@fudan.edu.cn> |
| Date: Sun, 19 Jul 2020 23:45:45 +0800 |
| Subject: [PATCH] drm: fix drm_dp_mst_port refcount leaks in |
| drm_dp_mst_allocate_vcpi |
| MIME-Version: 1.0 |
| Content-Type: text/plain; charset=UTF-8 |
| Content-Transfer-Encoding: 8bit |
| |
| commit a34a0a632dd991a371fec56431d73279f9c54029 upstream. |
| |
| drm_dp_mst_allocate_vcpi() invokes |
| drm_dp_mst_topology_get_port_validated(), which increases the refcount |
| of the "port". |
| |
| These reference counting issues take place in two exception handling |
| paths separately. Either when “slots” is less than 0 or when |
| drm_dp_init_vcpi() returns a negative value, the function forgets to |
| reduce the refcnt increased drm_dp_mst_topology_get_port_validated(), |
| which results in a refcount leak. |
| |
| Fix these issues by pulling up the error handling when "slots" is less |
| than 0, and calling drm_dp_mst_topology_put_port() before termination |
| when drm_dp_init_vcpi() returns a negative value. |
| |
| Fixes: 1e797f556c61 ("drm/dp: Split drm_dp_mst_allocate_vcpi") |
| Cc: <stable@vger.kernel.org> # v4.12+ |
| Signed-off-by: Xiyu Yang <xiyuyang19@fudan.edu.cn> |
| Signed-off-by: Xin Tan <tanxin.ctf@gmail.com> |
| Signed-off-by: Xin Xiong <xiongx18@fudan.edu.cn> |
| Reviewed-by: Lyude Paul <lyude@redhat.com> |
| Signed-off-by: Lyude Paul <lyude@redhat.com> |
| Link: https://patchwork.freedesktop.org/patch/msgid/20200719154545.GA41231@xin-virtual-machine |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com> |
| |
| diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c |
| index d4cc602a9bd5..aa6e6d88f30b 100644 |
| --- a/drivers/gpu/drm/drm_dp_mst_topology.c |
| +++ b/drivers/gpu/drm/drm_dp_mst_topology.c |
| @@ -3241,11 +3241,11 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, |
| { |
| int ret; |
| |
| - port = drm_dp_mst_topology_get_port_validated(mgr, port); |
| - if (!port) |
| + if (slots < 0) |
| return false; |
| |
| - if (slots < 0) |
| + port = drm_dp_mst_topology_get_port_validated(mgr, port); |
| + if (!port) |
| return false; |
| |
| if (port->vcpi.vcpi > 0) { |
| @@ -3261,6 +3261,7 @@ bool drm_dp_mst_allocate_vcpi(struct drm_dp_mst_topology_mgr *mgr, |
| if (ret) { |
| DRM_DEBUG_KMS("failed to init vcpi slots=%d max=63 ret=%d\n", |
| DIV_ROUND_UP(pbn, mgr->pbn_div), ret); |
| + drm_dp_mst_topology_put_port(port); |
| goto out; |
| } |
| DRM_DEBUG_KMS("initing vcpi for pbn=%d slots=%d\n", |
| -- |
| 2.27.0 |
| |