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Staging: sst: dereferencing user pointers

PATCH In review Dan Carpenter 2 participants 2 messages Oct 19, 2010 – Oct 21, 2010

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Dan Carpenter

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#0 lore raw

PATCH 1/3 Staging: sst: dereferencing user pointers

This code dereferences user supplied pointers directly instead of doing a copy_from_user(). Some kernel configs put user and kernel memory in different address spaces so this code isn't portable. Also the user memory could be swapped out or in this case the pointer could just be NULL leading to an oops.

Another thing is that it makes permission tests like this sort of meaningless.

	if (minor = STREAM_MODULE && rec_mute->stream_id = 0) {
		retval = -EPERM;
		break;
	}

The user could set stream_id to 1 for the test and then change it later.

Signed-off-by Dan Carpenter <[email protected]>
drivers/staging/intel_sst/intel_sst_app_interface.c +29 -36
index 463e5cb..a0d13ee 100644
@@ -885,41 +885,39 @@ long intel_sst_ioctl(struct file *file_ptr, unsigned int cmd, unsigned long arg)
 		break;
 	}
 	case _IOC_NR(SNDRV_SST_SET_VOL): {
-		struct snd_sst_vol *set_vol;
-		struct snd_sst_vol *rec_vol = (struct snd_sst_vol *)arg;
+		struct snd_sst_vol set_vol;
+
+		if (copy_from_user(&set_vol, (void __user *)arg,
+				sizeof(set_vol))) {
+			pr_debug("sst: copy failed\n");
+			retval = -EFAULT;
+			break;
+		}
 		pr_debug("sst: SET_VOLUME recieved for %d!\n",
-				rec_vol->stream_id);
-		if (minor = STREAM_MODULE && rec_vol->stream_id = 0) {
+				set_vol.stream_id);
+		if (minor = STREAM_MODULE && set_vol.stream_id = 0) {
 			pr_debug("sst: invalid operation!\n");
 			retval = -EPERM;
 			break;
 		}
-		set_vol = kzalloc(sizeof(*set_vol), GFP_ATOMIC);
-		if (!set_vol) {
-			pr_debug("sst: mem allocation failed\n");
-			retval = -ENOMEM;
-			break;
-		}
-		if (copy_from_user(set_vol, rec_vol, sizeof(*set_vol))) {
-			pr_debug("sst: copy failed\n");
-			retval = -EFAULT;
-			break;
-		}
-		retval = sst_set_vol(set_vol);
-		kfree(set_vol);
+		retval = sst_set_vol(&set_vol);
 		break;
 	}
 	case _IOC_NR(SNDRV_SST_GET_VOL): {
-		struct snd_sst_vol *rec_vol = (struct snd_sst_vol *)arg;
 		struct snd_sst_vol get_vol;
+
+		if (copy_from_user(&get_vol, (void __user *)arg,
+				sizeof(get_vol))) {
+			retval = -EFAULT;
+			break;
+		}
 		pr_debug("sst: IOCTL_GET_VOLUME recieved for stream = %d!\n",
-				rec_vol->stream_id);
-		if (minor = STREAM_MODULE && rec_vol->stream_id = 0) {
+				get_vol.stream_id);
+		if (minor = STREAM_MODULE && get_vol.stream_id = 0) {
 			pr_debug("sst: invalid operation!\n");
 			retval = -EPERM;
 			break;
 		}
-		get_vol.stream_id = rec_vol->stream_id;
 		retval = sst_get_vol(&get_vol);
 		if (retval) {
 			retval = -EIO;

@@ -938,25 +936,20 @@ long intel_sst_ioctl(struct file *file_ptr, unsigned int cmd, unsigned long arg)
 	}
 
 	case _IOC_NR(SNDRV_SST_MUTE): {
-		struct snd_sst_mute *set_mute;
-		struct snd_sst_vol *rec_mute = (struct snd_sst_vol *)arg;
-		pr_debug("sst: SNDRV_SST_SET_VOLUME recieved for %d!\n",
-			rec_mute->stream_id);
-		if (minor = STREAM_MODULE && rec_mute->stream_id = 0) {
-			retval = -EPERM;
-			break;
-		}
-		set_mute = kzalloc(sizeof(*set_mute), GFP_ATOMIC);
-		if (!set_mute) {
-			retval = -ENOMEM;
+		struct snd_sst_mute set_mute;
+
+		if (copy_from_user(&set_mute, (void __user *)arg,
+				sizeof(set_mute))) {
+			retval = -EFAULT;
 			break;
 		}
-		if (copy_from_user(set_mute, rec_mute, sizeof(*set_mute))) {
-			retval = -EFAULT;
+		pr_debug("sst: SNDRV_SST_SET_VOLUME recieved for %d!\n",
+			set_mute.stream_id);
+		if (minor = STREAM_MODULE && set_mute.stream_id = 0) {
+			retval = -EPERM;
 			break;
 		}
-		retval = sst_set_mute(set_mute);
-		kfree(set_mute);
+		retval = sst_set_mute(&set_mute);
 		break;
 	}
 	case _IOC_NR(SNDRV_SST_STREAM_GET_PARAMS): {
Acked-by on v1 1/3
#1 lore raw
Quoted 8 lines

This code dereferences user supplied pointers directly instead of doing a copy_from_user(). Some kernel configs put user and kernel memory in different address spaces so this code isn't portable. Also the user memory could be swapped out or in this case the pointer could just be NULL leading to an oops.

Another thing is that it makes permission tests like this sort of meaningless.

Quoted 7 lines
	if (minor = STREAM_MODULE && rec_mute->stream_id = 0) {
		retval = -EPERM;
		break;
	}

The user could set stream_id to 1 for the test and then change it later.

Signed-off-by Dan Carpenter <[email protected]>
Acked-by Vinod Koul <[email protected]>