patch "staging: bcm2835-audio: Fix memory corruption" added to staging-linus

[<gregkh@linuxfoundation.org>]

This is a note to let you know that I've just added the patch titled

    staging: bcm2835-audio: Fix memory corruption

to my staging git tree which can be found at
    git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/staging.git
in the staging-linus branch.

The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)

The patch will hopefully also be merged in Linus's tree for the
next -rc kernel release.

If you have any questions about this process, please let me know.


>From c97d96b4e612c7dc1b37d7afc61b598a9a25994d Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Sun, 24 Sep 2017 15:20:49 +0100
Subject: staging: bcm2835-audio: Fix memory corruption

The previous commit (0adbfd46) fixed a memory leak but also freed a
block in the success case, causing a stale pointer to be used with
potentially fatal results. Only free the vchi_instance block in the
case that vchi_connect fails; once connected, the instance is
retained for subsequent connections.

Simplifying the code by removing a bunch of gotos and returning errors
directly.

Signed-off-by: Phil Elwell <phil@raspberrypi.org>
Fixes: 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")
Cc: stable <stable@vger.kernel.org> # 4.12+
Tested-by: Stefan Wahren <stefan.wahren@i2se.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 .../vc04_services/bcm2835-audio/bcm2835-vchiq.c       | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

diff --git a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
index 5f3d8f2339e3..4be864dbd41c 100644
--- a/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
+++ b/drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c
@@ -390,8 +390,7 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream
 			__func__, instance);
 		instance->alsa_stream = alsa_stream;
 		alsa_stream->instance = instance;
-		ret = 0; // xxx todo -1;
-		goto err_free_mem;
+		return 0;
 	}
 
 	/* Initialize and create a VCHI connection */
@@ -401,16 +400,15 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream
 			LOG_ERR("%s: failed to initialise VCHI instance (ret=%d)\n",
 				__func__, ret);
 
-			ret = -EIO;
-			goto err_free_mem;
+			return -EIO;
 		}
 		ret = vchi_connect(NULL, 0, vchi_instance);
 		if (ret) {
 			LOG_ERR("%s: failed to connect VCHI instance (ret=%d)\n",
 				__func__, ret);
 
-			ret = -EIO;
-			goto err_free_mem;
+			kfree(vchi_instance);
+			return -EIO;
 		}
 		initted = 1;
 	}
@@ -421,19 +419,16 @@ static int bcm2835_audio_open_connection(struct bcm2835_alsa_stream *alsa_stream
 	if (IS_ERR(instance)) {
 		LOG_ERR("%s: failed to initialize audio service\n", __func__);
 
-		ret = PTR_ERR(instance);
-		goto err_free_mem;
+		/* vchi_instance is retained for use the next time. */
+		return PTR_ERR(instance);
 	}
 
 	instance->alsa_stream = alsa_stream;
 	alsa_stream->instance = instance;
 
 	LOG_DBG(" success !\n");
-	ret = 0;
-err_free_mem:
-	kfree(vchi_instance);
 
-	return ret;
+	return 0;
 }
 
 int bcm2835_audio_open(struct bcm2835_alsa_stream *alsa_stream)
-- 
2.14.2