diff --git a/fs/proc/base.c b/fs/proc/base.c
index 72a1acd03675..9e1cf6cc674d 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c

@@ -2740,6 +2740,7 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
 {
 	struct inode * inode = file_inode(file);
 	struct task_struct *task;
+	size_t wbytes;
 	void *page;
 	int rv;
 

@@ -2785,12 +2786,12 @@ static ssize_t proc_pid_attr_write(struct file * file, const char __user * buf,
 
 	rv = security_setprocattr(PROC_I(inode)->op.lsmid,
 				  file->f_path.dentry->d_name.name, page,
-				  count);
+				  count, &wbytes);
 	mutex_unlock(&current->signal->cred_guard_mutex);
 out_free:
 	kfree(page);
 out:
-	return rv;
+	return rv < 0 ? rv : wbytes;
 }
 
 static const struct file_operations proc_pid_attr_operations = {

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index dbc16f14f42f..2628514bb19c 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h

@@ -287,7 +287,8 @@ LSM_HOOK(int, -EOPNOTSUPP, setselfattr, unsigned int attr,
 	 struct lsm_ctx *ctx, u32 size, u32 flags)
 LSM_HOOK(int, -EINVAL, getprocattr, struct task_struct *p, const char *name,
 	 char **value)
-LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size)
+LSM_HOOK(int, -EINVAL, setprocattr, const char *name, void *value, size_t size,
+	 size_t *wbytes)
 LSM_HOOK(int, 0, ismaclabel, const char *name)
 LSM_HOOK(int, -EOPNOTSUPP, secid_to_secctx, u32 secid, char **secdata,
 	 u32 *seclen)

diff --git a/include/linux/security.h b/include/linux/security.h
index 96a63e132abf..1f1a9696e65d 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h

@@ -496,7 +496,8 @@ int security_setselfattr(unsigned int attr, struct lsm_ctx __user *ctx,
 			 u32 size, u32 flags);
 int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
 			 char **value);
-int security_setprocattr(int lsmid, const char *name, void *value, size_t size);
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size,
+			 size_t *wbytes);
 int security_netlink_send(struct sock *sk, struct sk_buff *skb);
 int security_ismaclabel(const char *name);
 int security_secid_to_secctx(u32 secid, char **secdata, u32 *seclen);

@@ -1440,7 +1441,7 @@ static inline int security_getprocattr(struct task_struct *p, int lsmid,
 }
 
 static inline int security_setprocattr(int lsmid, char *name, void *value,
-				       size_t size)
+				       size_t size, size_t *wbytes)
 {
 	return -EINVAL;
 }

diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
index 72dd09993f28..6c8b1f8c5781 100644
--- a/security/apparmor/lsm.c
+++ b/security/apparmor/lsm.c

@@ -939,13 +939,17 @@ static int apparmor_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
 }
 
 static int apparmor_setprocattr(const char *name, void *value,
-				size_t size)
+				size_t size, size_t *wbytes)
 {
+	int rc = -EINVAL;
 	int attr = lsm_name_to_attr(name);
 
 	if (attr)
-		return do_setattr(attr, value, size);
-	return -EINVAL;
+		rc = do_setattr(attr, value, size);
+	if (rc < 0)
+		return rc;
+	*wbytes = rc;
+	return 0;
 }
 
 /**

diff --git a/security/security.c b/security/security.c
index 095e78efcb32..9685096dbf16 100644
--- a/security/security.c
+++ b/security/security.c

@@ -4141,20 +4141,22 @@ int security_getprocattr(struct task_struct *p, int lsmid, const char *name,
  * @name: attribute name
  * @value: attribute value
  * @size: attribute value size
+ * @wbytes: bytes written on success
  *
  * Write (set) the current task's attribute @name to @value, size @size if
  * allowed.
  *
- * Return: Returns bytes written on success, a negative value otherwise.
+ * Return: Returns 0 on success, a negative error code otherwise.
  */
-int security_setprocattr(int lsmid, const char *name, void *value, size_t size)
+int security_setprocattr(int lsmid, const char *name, void *value, size_t size,
+			 size_t *wbytes)
 {
 	struct security_hook_list *hp;
 
 	hlist_for_each_entry(hp, &security_hook_heads.setprocattr, list) {
 		if (lsmid != 0 && lsmid != hp->lsmid->id)
 			continue;
-		return hp->hook.setprocattr(name, value, size);
+		return hp->hook.setprocattr(name, value, size, wbytes);
 	}
 	return LSM_RET_DEFAULT(setprocattr);
 }

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 0d35bb93baca..7a73f3710025 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c

@@ -6589,13 +6589,18 @@ static int selinux_getprocattr(struct task_struct *p,
 	return -EINVAL;
 }
 
-static int selinux_setprocattr(const char *name, void *value, size_t size)
+static int selinux_setprocattr(const char *name, void *value, size_t size,
+			       size_t *wbytes)
 {
+	int rc = -EINVAL;
 	int attr = lsm_name_to_attr(name);
 
 	if (attr)
-		return selinux_lsm_setattr(attr, value, size);
-	return -EINVAL;
+		rc = selinux_lsm_setattr(attr, value, size);
+	if (rc < 0)
+		return rc;
+	*wbytes = rc;
+	return 0;
 }
 
 static int selinux_ismaclabel(const char *name)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index 63d9c5f456c1..4265f2639106 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c

@@ -3797,19 +3797,25 @@ static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
  * @name: the name of the attribute in /proc/.../attr
  * @value: the value to set
  * @size: the size of the value
+ * @wbytes: the length of the smack label written
  *
  * Sets the Smack value of the task. Only setting self
  * is permitted and only with privilege
  *
- * Returns the length of the smack label or an error code
+ * Returns 0 on success or a negative error code
  */
-static int smack_setprocattr(const char *name, void *value, size_t size)
+static int smack_setprocattr(const char *name, void *value, size_t size,
+			     size_t *wbytes)
 {
+	int rc = -EINVAL;
 	int attr = lsm_name_to_attr(name);
 
 	if (attr != LSM_ATTR_UNDEF)
-		return do_setattr(attr, value, size);
-	return -EINVAL;
+		rc = do_setattr(attr, value, size);
+	if (rc < 0)
+		return rc;
+	*wbytes = rc;
+	return 0;
 }
 
 /**

-- 
2.30.2