linux-kernel - [PATCH] ASoC: Fix UBSAN warning at snd_soc_get/put_volsw

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Date:   Mon, 10 Sep 2018 23:03:56 +0530
From:   Rohit kumar <rohitkr@...eaurora.org>
To:     lgirdwood@...il.com, broonie@...nel.org, perex@...ex.cz,
        tiwai@...e.com, alsa-devel@...a-project.org,
        linux-kernel@...r.kernel.org, rohkumar@....qualcomm.com
Cc:     Rohit kumar <rohitkr@...eaurora.org>
Subject: [PATCH] ASoC: Fix UBSAN warning at snd_soc_get/put_volsw_sx()

In functions snd_soc_get_volsw_sx() or snd_soc_put_volsw_sx(),
if the result of (min + max) is negative, then fls() returns
signed integer with value as 32. This leads to signed integer
overflow as complete operation is considered as signed integer.

UBSAN: Undefined behaviour in sound/soc/soc-ops.c:382:50
signed integer overflow:
-2147483648 - 1 cannot be represented in type 'int'
Call trace:
[<ffffff852f746fe4>] __dump_stack lib/dump_stack.c:15 [inline]
[<ffffff852f746fe4>] dump_stack+0xec/0x158 lib/dump_stack.c:51
[<ffffff852f7b5f3c>] ubsan_epilogue+0x18/0x50 lib/ubsan.c:164
[<ffffff852f7b6840>] handle_overflow+0xf8/0x130 lib/ubsan.c:195
[<ffffff852f7b68f0>] __ubsan_handle_sub_overflow+0x34/0x44 lib/ubsan.c:211
[<ffffff85307971a0>] snd_soc_get_volsw_sx+0x1a8/0x1f8 sound/soc/soc-ops.c:382

Typecast the operation to unsigned int to fix the issue.

Signed-off-by: Rohit kumar <rohitkr@...eaurora.org>
---
 sound/soc/soc-ops.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/soc/soc-ops.c b/sound/soc/soc-ops.c
index 592efb3..f8e3190 100644
--- a/sound/soc/soc-ops.c
+++ b/sound/soc/soc-ops.c
@@ -373,7 +373,7 @@ int snd_soc_get_volsw_sx(struct snd_kcontrol *kcontrol,
 	unsigned int rshift = mc->rshift;
 	int max = mc->max;
 	int min = mc->min;
-	unsigned int mask = (1 << (fls(min + max) - 1)) - 1;
+	unsigned int mask = ((unsigned int)(1 << (fls(min + max) - 1)) - 1);
 	unsigned int val;
 	int ret;
 
@@ -418,7 +418,7 @@ int snd_soc_put_volsw_sx(struct snd_kcontrol *kcontrol,
 	unsigned int rshift = mc->rshift;
 	int max = mc->max;
 	int min = mc->min;
-	unsigned int mask = (1 << (fls(min + max) - 1)) - 1;
+	unsigned int mask = ((unsigned int)(1 << (fls(min + max) - 1)) - 1);
 	int err = 0;
 	unsigned int val, val_mask, val2 = 0;
 
-- 
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is a member of Code Aurora Forum, a Linux Foundation Collaborative Project.