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

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在 2022/9/10 1:27, sdf@xxxxxxxxxx 写道:
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.

Thanks for your comments.

It's my mistake.

Can I keep kvfree(value);    and send v2?


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




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