patches/0922-of-overlay-Fix-un-locking-in-of_overlay_apply.patch

From e914535cc137a9f4547d97e51a6a5cc755d9c676 Mon Sep 17 00:00:00 2001
From: Geert Uytterhoeven <geert+renesas@glider.be>
Date: Tue, 5 Dec 2017 16:27:03 +0100
Subject: [PATCH 0922/1795] of: overlay: Fix (un)locking in of_overlay_apply()

The special overlay mutex is taken first, hence it should be released
last in the error path.

of_resolve_phandles() must be called with of_mutex held.  Without it, a
node and new phandle could be added via of_attach_node(), making the max
phandle wrong.

free_overlay_changeset() must be called with of_mutex held, if any
non-trivial cleanup is to be done.

Hence move "mutex_lock(&of_mutex)" up, as suggested by Frank, and merge
the two tail statements of the success and error paths, now they became
identical.

Note that while the two mutexes are adjacent, we still need both:
__of_changeset_apply_notify(), which is called by __of_changeset_apply()
unlocks of_mutex, then does notifications then locks of_mutex.  So the
mutex get released in the middle of of_overlay_apply()

Fixes: f948d6d8b792bb90 ("of: overlay: avoid race condition between applying multiple overlays")
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Frank Rowand <frank.rowand@sony.com>
Signed-off-by: Rob Herring <robh@kernel.org>
(cherry picked from commit 5e4748175fe942c86cbab840e2fa41a92b4d6cf6)
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
---
 drivers/of/overlay.c | 15 +++++----------
 1 file changed, 5 insertions(+), 10 deletions(-)

diff --git a/drivers/of/overlay.c b/drivers/of/overlay.c
index bb3f123ed259..fcce5cdbe229 100644
--- a/drivers/of/overlay.c
+++ b/drivers/of/overlay.c
@@ -706,12 +706,11 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id)
 	}
 
 	of_overlay_mutex_lock();
+	mutex_lock(&of_mutex);
 
 	ret = of_resolve_phandles(tree);
 	if (ret)
-		goto err_overlay_unlock;
-
-	mutex_lock(&of_mutex);
+		goto err_free_overlay_changeset;
 
 	ret = init_overlay_changeset(ovcs, tree);
 	if (ret)
@@ -754,18 +753,14 @@ int of_overlay_apply(struct device_node *tree, int *ovcs_id)
 			ret = ret_tmp;
 	}
 
-	mutex_unlock(&of_mutex);
-	of_overlay_mutex_unlock();
-
-	goto out;
-
-err_overlay_unlock:
-	of_overlay_mutex_unlock();
+	goto out_unlock;
 
 err_free_overlay_changeset:
 	free_overlay_changeset(ovcs);
 
+out_unlock:
 	mutex_unlock(&of_mutex);
+	of_overlay_mutex_unlock();
 
 out:
 	pr_debug("%s() err=%d\n", __func__, ret);
-- 
2.19.0