staging: bcm2835-audio: Fix memory corruption

PATCH Superseded Phil Elwell 4 participants 5 messages Aug 11, 2017 – Sep 23, 2017

Subsystems (3)

Staging Broadcom BCM2711/BCM2835 Arm architecture Broadcom BCM281XX/BCM11XXX/BCM216XX Arm architecture

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Phil Elwell

author

2017-08-11 10:21 UTC #0 lore raw

PATCH v2 1/1 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 <[email protected]>

Fixes 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")

---
[Resend with v2 in subject]
v2: Simplified following feedback from Dan Carpenter.

---
 .../vc04_services/bcm2835-audio/bcm2835-vchiq.c       | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c +7 ~~-12~~

index 5f3d8f2..4be864d 100644
@@ -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)

Signature · 1 line

1.9.1

Dan Carpenter

2017-08-11 13:47 UTC #1 lore raw

Looks Ok to me.

regards,
dan carpenter

Stefan Wahren

2017-09-23 10:58 UTC #2 lore raw

In reply to Phil Elwell

Hi Greg,

Quoted 9 lines

Phil Elwell <[email protected]> hat am 11. August 2017 um 12:20 geschrieben:
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.

Quoted 5 lines

Simplifying the code by removing a bunch of gotos and returning errors directly.
Signed-off-by Phil Elwell <[email protected]>
Fixes 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")

can you still apply this patch or do you need a resend?

Quoted 67 lines

---
[Resend with v2 in subject]
v2: Simplified following feedback from Dan Carpenter.

---
 .../vc04_services/bcm2835-audio/bcm2835-vchiq.c       | 19 +++++++------------
 1 file changed, 7 insertions(+), 12 deletions(-)

drivers/staging/vc04_services/bcm2835-audio/bcm2835-vchiq.c +7 ~~-12~~

index 5f3d8f2..4be864d 100644
@@ -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)

Signature · 1 line

1.9.1

Greg Kroah-Hartman

maintainer

2017-09-23 16:15 UTC #3 lore raw

Quoted 11 lines · Stefan Wahren

Hi Greg,
Quoted 9 lines
Phil Elwell <[email protected]> hat am 11. August 2017 um 12:20 geschrieben:
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.

Quoted 7 lines

Quoted 5 lines
Simplifying the code by removing a bunch of gotos and returning errors directly.
Signed-off-by Phil Elwell <[email protected]>
Fixes 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")
can you still apply this patch or do you need a resend?

Hm, I don't see this anywhere in my tree, or in my todo mbox, so yes, please resend it, thanks.

greg k-h

Stefan Wahren

2017-09-23 22:45 UTC #4 lore raw

Hi Phil,

Quoted 18 lines

Greg Kroah-Hartman <[email protected]> hat am 23. September 2017 um 18:15 geschrieben:
Quoted 14 lines · Stefan Wahren
Hi Greg,
Quoted 12 lines
Phil Elwell <[email protected]> hat am 11. August 2017 um 12:20 geschrieben:
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.

Quoted 7 lines

Quoted 4 lines
Quoted 2 lines
Signed-off-by Phil Elwell <[email protected]>
Fixes 0adbfd4694c2 ("staging: bcm2835-audio: fix memory leak in bcm2835_audio_open_connection()")
can you still apply this patch or do you need a resend?
Hm, I don't see this anywhere in my tree, or in my todo mbox, so yes, please resend it, thanks.

could you please resend this patch?

Thanks
Stefan

Quoted 2 lines

greg k-h