linux-kernel - [PATCH] io_uring: fix mm use with IORING_OP

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Message-Id: <951bb84c8337aaac7654261a21b03506b2b8a001.1580914723.git.asml.silence@gmail.com>
Date:   Wed,  5 Feb 2020 18:46:14 +0300
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Jens Axboe <axboe@...nel.dk>, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: [PATCH] io_uring: fix mm use with IORING_OP_{READ,WRITE}

IORING_OP_{READ,WRITE} need mm to access user buffers, hence
req->has_user check should go for them as well. Move the corresponding
imports past the check.

Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
---
 fs/io_uring.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/fs/io_uring.c b/fs/io_uring.c
index edb00ae2619b..f00c2c9c67c0 100644
--- a/fs/io_uring.c
+++ b/fs/io_uring.c
@@ -2038,13 +2038,6 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
 	if (req->rw.kiocb.private)
 		return -EINVAL;
 
-	if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) {
-		ssize_t ret;
-		ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
-		*iovec = NULL;
-		return ret;
-	}
-
 	if (req->io) {
 		struct io_async_rw *iorw = &req->io->rw;
 
@@ -2058,6 +2051,13 @@ static ssize_t io_import_iovec(int rw, struct io_kiocb *req,
 	if (!req->has_user)
 		return -EFAULT;
 
+	if (opcode == IORING_OP_READ || opcode == IORING_OP_WRITE) {
+		ssize_t ret;
+		ret = import_single_range(rw, buf, sqe_len, *iovec, iter);
+		*iovec = NULL;
+		return ret;
+	}
+
 #ifdef CONFIG_COMPAT
 	if (req->ctx->compat)
 		return compat_import_iovec(rw, buf, sqe_len, UIO_FASTIOV,
-- 
2.24.0