linux-kernel - [PATCH 3.16 099/132] drivers/virt/fsl_hypervisor.c: dereferencing error pointers in ioctl

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Message-ID: <lsq.1568989415.737387212@decadent.org.uk>
Date:   Fri, 20 Sep 2019 15:23:35 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "Kumar Gala" <galak@...nel.crashing.org>,
        "Linus Torvalds" <torvalds@...ux-foundation.org>,
        "Timur Tabi" <timur@...escale.com>,
        "Dan Carpenter" <dan.carpenter@...cle.com>,
        "Mihai Caraman" <mihai.caraman@...escale.com>
Subject: [PATCH 3.16 099/132] drivers/virt/fsl_hypervisor.c: dereferencing
 error pointers in ioctl

3.16.74-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Dan Carpenter <dan.carpenter@...cle.com>

commit c8ea3663f7a8e6996d44500ee818c9330ac4fd88 upstream.

strndup_user() returns error pointers on error, and then in the error
handling we pass the error pointers to kfree().  It will cause an Oops.

Link: http://lkml.kernel.org/r/20181218082003.GD32567@kadam
Fixes: 6db7199407ca ("drivers/virt: introduce Freescale hypervisor management driver")
Signed-off-by: Dan Carpenter <dan.carpenter@...cle.com>
Reviewed-by: Andrew Morton <akpm@...ux-foundation.org>
Cc: Timur Tabi <timur@...escale.com>
Cc: Mihai Caraman <mihai.caraman@...escale.com>
Cc: Kumar Gala <galak@...nel.crashing.org>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@...ux-foundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/virt/fsl_hypervisor.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

--- a/drivers/virt/fsl_hypervisor.c
+++ b/drivers/virt/fsl_hypervisor.c
@@ -338,8 +338,8 @@ static long ioctl_dtprop(struct fsl_hv_i
 	struct fsl_hv_ioctl_prop param;
 	char __user *upath, *upropname;
 	void __user *upropval;
-	char *path = NULL, *propname = NULL;
-	void *propval = NULL;
+	char *path, *propname;
+	void *propval;
 	int ret = 0;
 
 	/* Get the parameters from the user. */
@@ -351,32 +351,30 @@ static long ioctl_dtprop(struct fsl_hv_i
 	upropval = (void __user *)(uintptr_t)param.propval;
 
 	path = strndup_user(upath, FH_DTPROP_MAX_PATHLEN);
-	if (IS_ERR(path)) {
-		ret = PTR_ERR(path);
-		goto out;
-	}
+	if (IS_ERR(path))
+		return PTR_ERR(path);
 
 	propname = strndup_user(upropname, FH_DTPROP_MAX_PATHLEN);
 	if (IS_ERR(propname)) {
 		ret = PTR_ERR(propname);
-		goto out;
+		goto err_free_path;
 	}
 
 	if (param.proplen > FH_DTPROP_MAX_PROPLEN) {
 		ret = -EINVAL;
-		goto out;
+		goto err_free_propname;
 	}
 
 	propval = kmalloc(param.proplen, GFP_KERNEL);
 	if (!propval) {
 		ret = -ENOMEM;
-		goto out;
+		goto err_free_propname;
 	}
 
 	if (set) {
 		if (copy_from_user(propval, upropval, param.proplen)) {
 			ret = -EFAULT;
-			goto out;
+			goto err_free_propval;
 		}
 
 		param.ret = fh_partition_set_dtprop(param.handle,
@@ -395,7 +393,7 @@ static long ioctl_dtprop(struct fsl_hv_i
 			if (copy_to_user(upropval, propval, param.proplen) ||
 			    put_user(param.proplen, &p->proplen)) {
 				ret = -EFAULT;
-				goto out;
+				goto err_free_propval;
 			}
 		}
 	}
@@ -403,10 +401,12 @@ static long ioctl_dtprop(struct fsl_hv_i
 	if (put_user(param.ret, &p->ret))
 		ret = -EFAULT;
 
-out:
-	kfree(path);
+err_free_propval:
 	kfree(propval);
+err_free_propname:
 	kfree(propname);
+err_free_path:
+	kfree(path);
 
 	return ret;
 }