linux-kernel - [PATCH v2 bpf-next] bpf: Fix memory leaks in generic update/delete batch ops

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Message-Id: <20200119194040.128369-1-brianvv@google.com>
Date:   Sun, 19 Jan 2020 11:40:40 -0800
From:   Brian Vazquez <brianvv@...gle.com>
To:     Brian Vazquez <brianvv.kernel@...il.com>,
        Brian Vazquez <brianvv@...gle.com>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        "David S . Miller" <davem@...emloft.net>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        bpf@...r.kernel.org, Dan Carpenter <dan.carpenter@...cle.com>,
        Yonghong Song <yhs@...com>
Subject: [PATCH v2 bpf-next] bpf: Fix memory leaks in generic update/delete
 batch ops

generic update/delete batch ops functions were using __bpf_copy_key
without properly freeing the memory. Handle the memory allocation and
copy_from_user separately.

Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops")
Signed-off-by: Brian Vazquez <brianvv@...gle.com>
Acked-by: Yonghong Song <yhs@...com>
---
v1->v2:
 - Put Fixes subject in a single line (Yonghong Song)
---
 kernel/bpf/syscall.c | 30 +++++++++++++++++++-----------
 1 file changed, 19 insertions(+), 11 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c26a71460f02f..9a840c57f6df7 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1239,12 +1239,15 @@ int generic_map_delete_batch(struct bpf_map *map,
 	if (!max_count)
 		return 0;
 
+	key = kmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
+	if (!key)
+		return -ENOMEM;
+
 	for (cp = 0; cp < max_count; cp++) {
-		key = __bpf_copy_key(keys + cp * map->key_size, map->key_size);
-		if (IS_ERR(key)) {
-			err = PTR_ERR(key);
+		err = -EFAULT;
+		if (copy_from_user(key, keys + cp * map->key_size,
+				   map->key_size))
 			break;
-		}
 
 		if (bpf_map_is_dev_bound(map)) {
 			err = bpf_map_offload_delete_elem(map, key);
@@ -1264,6 +1267,8 @@ int generic_map_delete_batch(struct bpf_map *map,
 	}
 	if (copy_to_user(&uattr->batch.count, &cp, sizeof(cp)))
 		err = -EFAULT;
+
+	kfree(key);
 	return err;
 }
 
@@ -1294,18 +1299,21 @@ int generic_map_update_batch(struct bpf_map *map,
 	if (!max_count)
 		return 0;
 
+	key = kmalloc(map->key_size, GFP_USER | __GFP_NOWARN);
+	if (!key)
+		return -ENOMEM;
+
 	value = kmalloc(value_size, GFP_USER | __GFP_NOWARN);
-	if (!value)
+	if (!value) {
+		kfree(key);
 		return -ENOMEM;
+	}
 
 	for (cp = 0; cp < max_count; cp++) {
-		key = __bpf_copy_key(keys + cp * map->key_size, map->key_size);
-		if (IS_ERR(key)) {
-			err = PTR_ERR(key);
-			break;
-		}
 		err = -EFAULT;
-		if (copy_from_user(value, values + cp * value_size, value_size))
+		if (copy_from_user(key, keys + cp * map->key_size,
+		    map->key_size) ||
+		    copy_from_user(value, values + cp * value_size, value_size))
 			break;
 
 		err = bpf_map_update_value(map, f, key, value,
-- 
2.25.0.341.g760bfbb309-goog