linux-kernel - [PATCH 4.4 19/48] ALSA: hwdep: fix a left shifting 1 by 31 UB bug

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Date:   Mon,  1 Jun 2020 19:53:29 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        Changming Liu <liu.changm@...theastern.edu>,
        Takashi Iwai <tiwai@...e.de>, Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 19/48] ALSA: hwdep: fix a left shifting 1 by 31 UB bug

From: Changming Liu <liu.changm@...theastern.edu>

[ Upstream commit fb8cd6481ffd126f35e9e146a0dcf0c4e8899f2e ]

The "info.index" variable can be 31 in "1 << info.index".
This might trigger an undefined behavior since 1 is signed.

Fix this by casting 1 to 1u just to be sure "1u << 31" is defined.

Signed-off-by: Changming Liu <liu.changm@...theastern.edu>
Cc: <stable@...r.kernel.org>
Link: https://lore.kernel.org/r/BL0PR06MB4548170B842CB055C9AF695DE5B00@BL0PR06MB4548.namprd06.prod.outlook.com
Signed-off-by: Takashi Iwai <tiwai@...e.de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 sound/core/hwdep.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/sound/core/hwdep.c b/sound/core/hwdep.c
index 36d2416f90d9..96b737adf4d2 100644
--- a/sound/core/hwdep.c
+++ b/sound/core/hwdep.c
@@ -228,14 +228,14 @@ static int snd_hwdep_dsp_load(struct snd_hwdep *hw,
 	if (copy_from_user(&info, _info, sizeof(info)))
 		return -EFAULT;
 	/* check whether the dsp was already loaded */
-	if (hw->dsp_loaded & (1 << info.index))
+	if (hw->dsp_loaded & (1u << info.index))
 		return -EBUSY;
 	if (!access_ok(VERIFY_READ, info.image, info.length))
 		return -EFAULT;
 	err = hw->ops.dsp_load(hw, &info);
 	if (err < 0)
 		return err;
-	hw->dsp_loaded |= (1 << info.index);
+	hw->dsp_loaded |= (1u << info.index);
 	return 0;
 }
 
-- 
2.25.1