get_compat_bpf_fprog(): don't copyin field-by-field

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

diff --git a/net/compat.c b/net/compat.c
index dba5e222a0e5bf625c3866e4e55bd88339d750d8..6ded6c821d7a21f296d14db02552ea1c71643051 100644 (file)
--- a/net/compat.c
+++ b/net/compat.c
@@ -313,15 +313,15 @@ struct sock_fprog __user *get_compat_bpf_fprog(char __user *optval)
 {
        struct compat_sock_fprog __user *fprog32 = (struct compat_sock_fprog __user *)optval;
        struct sock_fprog __user *kfprog = compat_alloc_user_space(sizeof(struct sock_fprog));
-       compat_uptr_t ptr;
-       u16 len;
-
-       if (!access_ok(VERIFY_READ, fprog32, sizeof(*fprog32)) ||
-           !access_ok(VERIFY_WRITE, kfprog, sizeof(struct sock_fprog)) ||
-           __get_user(len, &fprog32->len) ||
-           __get_user(ptr, &fprog32->filter) ||
-           __put_user(len, &kfprog->len) ||
-           __put_user(compat_ptr(ptr), &kfprog->filter))
+       struct compat_sock_fprog f32;
+       struct sock_fprog f;
+
+       if (copy_from_user(&f32, fprog32, sizeof(*fprog32)))
+               return NULL;
+       memset(&f, 0, sizeof(f));
+       f.len = f32.len;
+       f.filter = compat_ptr(f32.filter);
+       if (copy_to_user(kfprog, &f, sizeof(struct sock_fprog)))
                return NULL;
 
        return kfprog;