[PATCH bpf-next v2] bpf: Clean code with bpf_copy_to_user

[Tao Chen <chen.dylane@linux.dev>]

No logic change, just use bpf_copy_to_user to clean code.

Signed-off-by: Tao Chen <chen.dylane@linux.dev>
---
 kernel/bpf/syscall.c | 17 +++--------------
 1 file changed, 3 insertions(+), 14 deletions(-)

Change list:
  v1 -> v2:
    - do not directly return when handle err ENOSPC.(Yonghong)
  v1:
    https://lore.kernel.org/bpf/20250703124336.672416-1-chen.dylane@linux.dev

diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index e6eea594f1c..6ea3a8e3f7e 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -5208,21 +5208,10 @@ static int bpf_task_fd_query_copy(const union bpf_attr *attr,
 
 			if (put_user(zero, ubuf))
 				return -EFAULT;
-		} else if (input_len >= len + 1) {
-			/* ubuf can hold the string with NULL terminator */
-			if (copy_to_user(ubuf, buf, len + 1))
-				return -EFAULT;
 		} else {
-			/* ubuf cannot hold the string with NULL terminator,
-			 * do a partial copy with NULL terminator.
-			 */
-			char zero = '\0';
-
-			err = -ENOSPC;
-			if (copy_to_user(ubuf, buf, input_len - 1))
-				return -EFAULT;
-			if (put_user(zero, ubuf + input_len - 1))
-				return -EFAULT;
+			err = bpf_copy_to_user(ubuf, buf, input_len, len);
+			if (err == -EFAULT)
+				return err;
 		}
 	}
 
-- 
2.48.1