From: Pavel Begunkov <asml.silence@gmail.com>
Date: Mon, 24 Feb 2025 12:42:22 +0000 (+0000)
Subject: io_uring/rw: shrink io_iov_compat_buffer_select_prep
X-Git-Tag: v6.15-rc1~167^2~75
X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=52524b281d5746cf9dbd53a7dffce9576e8ddd30;p=thirdparty%2Fkernel%2Flinux.git

io_uring/rw: shrink io_iov_compat_buffer_select_prep

Compat performance is not important and simplicity is more appreciated.
Let's not be smart about it and use simpler copy_from_user() instead of
access + __get_user pair.

Signed-off-by: Pavel Begunkov <asml.silence@gmail.com>
Link: https://lore.kernel.org/r/b334a3a5040efa424ded58e4d8a6ef2554324266.1740400452.git.asml.silence@gmail.com
Signed-off-by: Jens Axboe <axboe@kernel.dk>
---

diff --git a/io_uring/rw.c b/io_uring/rw.c
index 7133029b43966..22612a956e75a 100644
--- a/io_uring/rw.c
+++ b/io_uring/rw.c
@@ -48,18 +48,12 @@ static bool io_file_supports_nowait(struct io_kiocb *req, __poll_t mask)
 
 static int io_iov_compat_buffer_select_prep(struct io_rw *rw)
 {
-	struct compat_iovec __user *uiov;
-	compat_ssize_t clen;
+	struct compat_iovec __user *uiov = u64_to_user_ptr(rw->addr);
+	struct compat_iovec iov;
 
-	uiov = u64_to_user_ptr(rw->addr);
-	if (!access_ok(uiov, sizeof(*uiov)))
-		return -EFAULT;
-	if (__get_user(clen, &uiov->iov_len))
+	if (copy_from_user(&iov, uiov, sizeof(iov)))
 		return -EFAULT;
-	if (clen < 0)
-		return -EINVAL;
-
-	rw->len = clen;
+	rw->len = iov.iov_len;
 	return 0;
 }