From 6525bfbd546f9bbbcbe0678b2985697a3a7b2bcb Mon Sep 17 00:00:00 2001
From: Xu Kuohai <xukuohai@huawei.com>
Date: Tue, 19 Oct 2021 03:29:34 +0000
Subject: [PATCH] bpf: Fix error usage of map_fd and fdget() in generic_map_update_batch()
Git-commit: fda7a38714f40b635f5502ec4855602c6b33dad2
Patch-mainline: v5.15
References: stable-5.14.16

commit fda7a38714f40b635f5502ec4855602c6b33dad2 upstream.

1. The ufd in generic_map_update_batch() should be read from batch.map_fd;
2. A call to fdget() should be followed by a symmetric call to fdput().

Fixes: aa2e93b8e58e ("bpf: Add generic support for update and delete batch ops")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20211019032934.1210517-1-xukuohai@huawei.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 kernel/bpf/syscall.c |    5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1325,12 +1325,11 @@ int generic_map_update_batch(struct bpf_
 	void __user *values = u64_to_user_ptr(attr->batch.values);
 	void __user *keys = u64_to_user_ptr(attr->batch.keys);
 	u32 value_size, cp, max_count;
-	int ufd = attr->map_fd;
+	int ufd = attr->batch.map_fd;
 	void *key, *value;
 	struct fd f;
 	int err = 0;
 
-	f = fdget(ufd);
 	if (attr->batch.elem_flags & ~BPF_F_LOCK)
 		return -EINVAL;
 
@@ -1355,6 +1354,7 @@ int generic_map_update_batch(struct bpf_
 		return -ENOMEM;
 	}
 
+	f = fdget(ufd); /* bpf_map_do_batch() guarantees ufd is valid */
 	for (cp = 0; cp < max_count; cp++) {
 		err = -EFAULT;
 		if (copy_from_user(key, keys + cp * map->key_size,
@@ -1374,6 +1374,7 @@ int generic_map_update_batch(struct bpf_
 
 	kvfree(value);
 	kvfree(key);
+	fdput(f);
 	return err;
 }