commit f8f8a727eab1c5b78c3703a461565b042979cc79
author Al Viro <viro@zeniv.linux.org.uk> Tue Jun 27 18:34:53 2017 -0400
committer Al Viro <viro@zeniv.linux.org.uk> Tue Jul 04 13:14:34 2017 -0400
tree 1614a24192411d84b48c2f383fe3339666fc92a4
parent 5da028a8af38eced330332d5ae51c212e9e86242

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

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

net/compat.c

diff --git a/net/compat.c b/net/compat.c
index dba5e22..6ded6c8 100644
--- a/net/compat.c
+++ b/net/compat.c
@@ -313,15 +313,15 @@
 {
 	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;
+	struct compat_sock_fprog f32;
+	struct sock_fprog f;
 
-	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))
+	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;