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Date:   Fri, 10 Jan 2020 14:56:02 -0800
Message-Id: <20200110225602.91663-1-samitolvanen@google.com>
Mime-Version: 1.0
Subject: [PATCH] lib/list_sort: fix function type mismatches
From:   Sami Tolvanen <samitolvanen@google.com>
To:     Andrew Morton <akpm@linux-foundation.org>,
        Andrey Abramov <st5pub@yandex.ru>,
        Rasmus Villemoes <linux@rasmusvillemoes.dk>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        George Spelvin <lkml@sdf.org>,
        Mauro Carvalho Chehab <mchehab+samsung@kernel.org>,
        Kees Cook <keescook@chromium.org>
Cc:     linux-kernel@vger.kernel.org,
        Sami Tolvanen <samitolvanen@google.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

Casting the comparison function to a different type trips indirect call
Control-Flow Integrity (CFI) checking. Remove the additional consts from
cmp_func, and the now unneeded casts.

Fixes: 043b3f7b6388 ("lib/list_sort: simplify and remove MAX_LIST_LENGTH_BITS")
Signed-off-by: Sami Tolvanen <samitolvanen@google.com>
---
 lib/list_sort.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/lib/list_sort.c b/lib/list_sort.c
index 52f0c258c895..b14accf4ef83 100644
--- a/lib/list_sort.c
+++ b/lib/list_sort.c
@@ -8,7 +8,7 @@
 #include <linux/list.h>
 
 typedef int __attribute__((nonnull(2,3))) (*cmp_func)(void *,
-		struct list_head const *, struct list_head const *);
+		struct list_head *, struct list_head *);
 
 /*
  * Returns a list organized in an intermediate format suited
@@ -227,7 +227,7 @@ void list_sort(void *priv, struct list_head *head,
 		if (likely(bits)) {
 			struct list_head *a = *tail, *b = a->prev;
 
-			a = merge(priv, (cmp_func)cmp, b, a);
+			a = merge(priv, cmp, b, a);
 			/* Install the merged result in place of the inputs */
 			a->prev = b->prev;
 			*tail = a;
@@ -249,10 +249,10 @@ void list_sort(void *priv, struct list_head *head,
 
 		if (!next)
 			break;
-		list = merge(priv, (cmp_func)cmp, pending, list);
+		list = merge(priv, cmp, pending, list);
 		pending = next;
 	}
 	/* The final merge, rebuilding prev links */
-	merge_final(priv, (cmp_func)cmp, head, pending, list);
+	merge_final(priv, cmp, head, pending, list);
 }
 EXPORT_SYMBOL(list_sort);

base-commit: ac61145a725ab0411c5f8ed9aeca6202076ecfd8
-- 
2.25.0.rc1.283.g88dfdc4193-goog