From 100294cee9a98bfd4d6cb2d1c8a8aef0e959b0c4 Mon Sep 17 00:00:00 2001
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: Mon, 6 Aug 2018 15:10:40 -0700
Subject: [PATCH] Input: do not use WARN() in input_alloc_absinfo()
Git-commit: 100294cee9a98bfd4d6cb2d1c8a8aef0e959b0c4
References: git-fixes
Patch-mainline: v4.19-rc1

Some of fuzzers set panic_on_warn=1 so that they can handle WARN()ings
the same way they handle full-blown kernel crashes. We used WARN() in
input_alloc_absinfo() to get a better idea where memory allocation
failed, but since then kmalloc() and friends started dumping call stack on
memory allocation failures anyway, so we are not getting anything extra
from WARN().

Because of the above, let's replace WARN with dev_err(). We use dev_err()
instead of simply removing message and relying on kcalloc() to give us
stack dump so that we'd know the instance of hardware device to which we
were trying to attach input device.

Reported-by: Dmitry Vyukov <dvyukov@google.com>
Acked-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Oliver Neukum <oneukum@suse.com>
---
 drivers/input/input.c | 16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

diff --git a/drivers/input/input.c b/drivers/input/input.c
index 6365c1958264..3304aaaffe87 100644
--- a/drivers/input/input.c
+++ b/drivers/input/input.c
@@ -480,11 +480,19 @@ EXPORT_SYMBOL(input_inject_event);
  */
 void input_alloc_absinfo(struct input_dev *dev)
 {
-	if (!dev->absinfo)
-		dev->absinfo = kcalloc(ABS_CNT, sizeof(*dev->absinfo),
-					GFP_KERNEL);
+	if (dev->absinfo)
+		return;
 
-	WARN(!dev->absinfo, "%s(): kcalloc() failed?\n", __func__);
+	dev->absinfo = kcalloc(ABS_CNT, sizeof(*dev->absinfo), GFP_KERNEL);
+	if (!dev->absinfo) {
+		dev_err(dev->dev.parent ?: &dev->dev,
+			"%s: unable to allocate memory\n", __func__);
+		/*
+		 * We will handle this allocation failure in
+		 * input_register_device() when we refuse to register input
+		 * device with ABS bits but without absinfo.
+		 */
+	}
 }
 EXPORT_SYMBOL(input_alloc_absinfo);
 
-- 
2.39.0