From: Maxime Ripard maxime@cerno.tech
commit d134c5ff71c7f2320fc7997f2fbbdedf0c76889a upstream.
Commit 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit") introduced a wait on the previous commit done on a given HVS FIFO.
However, we never cleared that pointer once done. Since drm_crtc_commit_put can free the drm_crtc_commit structure directly if we were the last user, this means that it can lead to a use-after free if we were to duplicate the state, and that stale pointer would even be copied to the new state.
Set the pointer to NULL once we're done with the wait so that we don't carry over a pointer to a free'd structure.
Fixes: 9ec03d7f1ed3 ("drm/vc4: kms: Wait on previous FIFO users before a commit") Signed-off-by: Maxime Ripard maxime@cerno.tech Reviewed-by: Dave Stevenson dave.stevenson@raspberrypi.com Tested-by: Jian-Hong Pan jhp@endlessos.org Link: https://lore.kernel.org/r/20211117094527.146275-5-maxime@cerno.tech Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/vc4/vc4_kms.c | 1 + 1 file changed, 1 insertion(+)
--- a/drivers/gpu/drm/vc4/vc4_kms.c +++ b/drivers/gpu/drm/vc4/vc4_kms.c @@ -379,6 +379,7 @@ static void vc4_atomic_commit_tail(struc drm_err(dev, "Timed out waiting for commit\n");
drm_crtc_commit_put(commit); + old_hvs_state->fifo_state[channel].pending_commit = NULL; }
if (vc4->hvs->hvs5)