Re: [bpf-next] bpf: use kvmemdup_bpfptr helper

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On 09/09, Wang Yufen wrote:
Use kvmemdup_bpfptr helper instead of open-coding to
simplify the code.

Signed-off-by: Wang Yufen <wangyufen@xxxxxxxxxx>
---
  kernel/bpf/syscall.c | 14 ++++----------
  1 file changed, 4 insertions(+), 10 deletions(-)

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4e9d4622aef7..13ce28081982 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -1413,20 +1413,14 @@ static int map_update_elem(union bpf_attr *attr, bpfptr_t uattr)
  	}

  	value_size = bpf_map_value_size(map);
-
-	err = -ENOMEM;
-	value = kvmalloc(value_size, GFP_USER | __GFP_NOWARN);
-	if (!value)
+	value = kvmemdup_bpfptr(uvalue, value_size);
+	if (IS_ERR(value)) {
+		err = PTR_ERR(value);
  		goto free_key;
-
-	err = -EFAULT;
-	if (copy_from_bpfptr(value, uvalue, value_size) != 0)
-		goto free_value;
+	}

  	err = bpf_map_update_value(map, f, key, value, attr->flags);


[..]

-free_value:
-	kvfree(value);

And here you leak the value. We need to free it after update regardless
of error/success. That's why it is coded like that.

  free_key:
  	kvfree(key);
  err_put:
--
2.25.1




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