Heh, I remember this being mentioned to me way back but completely forgot to ever go fix it. Thanks for the patch!
Reviewed-by: Lyude Paul lyude@redhat.com
This is missing a Fixes: tag though:
Fixes: 1e797f556c61 ("drm/dp: Split drm_dp_mst_allocate_vcpi") Cc: stable@vger.kernel.org # v4.12+
So I will go ahead and add that, then push this to drm-misc-next-fixes. Thanks!
On Sun, 2020-07-19 at 23:45 +0800, Xin Xiong wrote:
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.
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
drivers/gpu/drm/drm_dp_mst_topology.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/drm_dp_mst_topology.c b/drivers/gpu/drm/drm_dp_mst_topology.c index 1e26b89628f9..97b48b531ec6 100644 --- a/drivers/gpu/drm/drm_dp_mst_topology.c +++ b/drivers/gpu/drm/drm_dp_mst_topology.c @@ -4261,11 +4261,11 @@ 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) {
@@ -4281,6 +4281,7 @@ 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);