From: Al Viro <viro@zeniv.linux.org.uk>
Date: Sat, 13 May 2017 18:43:00 -0400
Subject: bpf: don't open-code memdup_user()
Patch-mainline: v4.13-rc1
Git-commit: e4448ed87ccdbacb74871736f63220642242b32f
References: bsc#1056787

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Acked-by: Thomas Bogendoerfer <tbogendoerfer@suse.de>
---
 kernel/bpf/syscall.c |   45 ++++++++++++++++-----------------------------
 1 file changed, 16 insertions(+), 29 deletions(-)

--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -410,14 +410,11 @@ static int map_lookup_elem(union bpf_att
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
-	err = -ENOMEM;
-	key = kmalloc(map->key_size, GFP_USER);
-	if (!key)
+	key = memdup_user(ukey, map->key_size);
+	if (IS_ERR(key)) {
+		err = PTR_ERR(key);
 		goto err_put;
-
-	err = -EFAULT;
-	if (copy_from_user(key, ukey, map->key_size) != 0)
-		goto free_key;
+	}
 
 	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
@@ -493,14 +490,11 @@ static int map_update_elem(union bpf_att
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
-	err = -ENOMEM;
-	key = kmalloc(map->key_size, GFP_USER);
-	if (!key)
+	key = memdup_user(ukey, map->key_size);
+	if (IS_ERR(key)) {
+		err = PTR_ERR(key);
 		goto err_put;
-
-	err = -EFAULT;
-	if (copy_from_user(key, ukey, map->key_size) != 0)
-		goto free_key;
+	}
 
 	if (map->map_type == BPF_MAP_TYPE_PERCPU_HASH ||
 	    map->map_type == BPF_MAP_TYPE_LRU_PERCPU_HASH ||
@@ -579,14 +573,11 @@ static int map_delete_elem(union bpf_att
 	if (IS_ERR(map))
 		return PTR_ERR(map);
 
-	err = -ENOMEM;
-	key = kmalloc(map->key_size, GFP_USER);
-	if (!key)
+	key = memdup_user(ukey, map->key_size);
+	if (IS_ERR(key)) {
+		err = PTR_ERR(key);
 		goto err_put;
-
-	err = -EFAULT;
-	if (copy_from_user(key, ukey, map->key_size) != 0)
-		goto free_key;
+	}
 
 	preempt_disable();
 	__this_cpu_inc(bpf_prog_active);
@@ -598,7 +589,6 @@ static int map_delete_elem(union bpf_att
 
 	if (!err)
 		trace_bpf_map_delete_elem(map, ufd, key);
-free_key:
 	kfree(key);
 err_put:
 	fdput(f);
@@ -627,14 +617,11 @@ static int map_get_next_key(union bpf_at
 		return PTR_ERR(map);
 
 	if (ukey) {
-		err = -ENOMEM;
-		key = kmalloc(map->key_size, GFP_USER);
-		if (!key)
+		key = memdup_user(ukey, map->key_size);
+		if (IS_ERR(key)) {
+			err = PTR_ERR(key);
 			goto err_put;
-
-		err = -EFAULT;
-		if (copy_from_user(key, ukey, map->key_size) != 0)
-			goto free_key;
+		}
 	} else {
 		key = NULL;
 	}