[PATCH v2 4/6] aio: shift copyin of iocb into io_submit_one()

[Al Viro <viro@xxxxxxxxxxxxxxxxxx>]

From: Al Viro <viro@xxxxxxxxxxxxxxxxxx>

Reviewed-by: Christoph Hellwig <hch@xxxxxx>
Signed-off-by: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
---
 fs/aio.c | 46 ++++++++++++++++++++++------------------------
 1 file changed, 22 insertions(+), 24 deletions(-)

diff --git a/fs/aio.c b/fs/aio.c
index 51843b057841..dca104883f0f 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -1723,22 +1723,26 @@ static ssize_t aio_poll(struct aio_kiocb *aiocb, struct iocb *iocb)
 }
 
 static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
-			 struct iocb *iocb, bool compat)
+			 bool compat)
 {
 	struct aio_kiocb *req;
+	struct iocb iocb;
 	ssize_t ret;
 
+	if (unlikely(copy_from_user(&iocb, user_iocb, sizeof(iocb))))
+		return -EFAULT;
+
 	/* enforce forwards compatibility on users */
-	if (unlikely(iocb->aio_reserved2)) {
+	if (unlikely(iocb.aio_reserved2)) {
 		pr_debug("EINVAL: reserve field set\n");
 		return -EINVAL;
 	}
 
 	/* prevent overflows */
 	if (unlikely(
-	    (iocb->aio_buf != (unsigned long)iocb->aio_buf) ||
-	    (iocb->aio_nbytes != (size_t)iocb->aio_nbytes) ||
-	    ((ssize_t)iocb->aio_nbytes < 0)
+	    (iocb.aio_buf != (unsigned long)iocb.aio_buf) ||
+	    (iocb.aio_nbytes != (size_t)iocb.aio_nbytes) ||
+	    ((ssize_t)iocb.aio_nbytes < 0)
 	   )) {
 		pr_debug("EINVAL: overflow check\n");
 		return -EINVAL;
@@ -1748,14 +1752,14 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	if (unlikely(!req))
 		return -EAGAIN;
 
-	if (iocb->aio_flags & IOCB_FLAG_RESFD) {
+	if (iocb.aio_flags & IOCB_FLAG_RESFD) {
 		/*
 		 * If the IOCB_FLAG_RESFD flag of aio_flags is set, get an
 		 * instance of the file* now. The file descriptor must be
 		 * an eventfd() fd, and will be signaled for each completed
 		 * event using the eventfd_signal() function.
 		 */
-		req->ki_eventfd = eventfd_ctx_fdget((int) iocb->aio_resfd);
+		req->ki_eventfd = eventfd_ctx_fdget((int) iocb.aio_resfd);
 		if (IS_ERR(req->ki_eventfd)) {
 			ret = PTR_ERR(req->ki_eventfd);
 			req->ki_eventfd = NULL;
@@ -1770,32 +1774,32 @@ static int io_submit_one(struct kioctx *ctx, struct iocb __user *user_iocb,
 	}
 
 	req->ki_user_iocb = user_iocb;
-	req->ki_user_data = iocb->aio_data;
+	req->ki_user_data = iocb.aio_data;
 
-	switch (iocb->aio_lio_opcode) {
+	switch (iocb.aio_lio_opcode) {
 	case IOCB_CMD_PREAD:
-		ret = aio_read(&req->rw, iocb, false, compat);
+		ret = aio_read(&req->rw, &iocb, false, compat);
 		break;
 	case IOCB_CMD_PWRITE:
-		ret = aio_write(&req->rw, iocb, false, compat);
+		ret = aio_write(&req->rw, &iocb, false, compat);
 		break;
 	case IOCB_CMD_PREADV:
-		ret = aio_read(&req->rw, iocb, true, compat);
+		ret = aio_read(&req->rw, &iocb, true, compat);
 		break;
 	case IOCB_CMD_PWRITEV:
-		ret = aio_write(&req->rw, iocb, true, compat);
+		ret = aio_write(&req->rw, &iocb, true, compat);
 		break;
 	case IOCB_CMD_FSYNC:
-		ret = aio_fsync(&req->fsync, iocb, false);
+		ret = aio_fsync(&req->fsync, &iocb, false);
 		break;
 	case IOCB_CMD_FDSYNC:
-		ret = aio_fsync(&req->fsync, iocb, true);
+		ret = aio_fsync(&req->fsync, &iocb, true);
 		break;
 	case IOCB_CMD_POLL:
-		ret = aio_poll(req, iocb);
+		ret = aio_poll(req, &iocb);
 		break;
 	default:
-		pr_debug("invalid aio operation %d\n", iocb->aio_lio_opcode);
+		pr_debug("invalid aio operation %d\n", iocb.aio_lio_opcode);
 		ret = -EINVAL;
 		break;
 	}
@@ -1848,19 +1852,13 @@ static long do_io_submit(aio_context_t ctx_id, long nr,
 	 */
 	for (i=0; i<nr; i++) {
 		struct iocb __user *user_iocb;
-		struct iocb tmp;
 
 		if (unlikely(__get_user(user_iocb, iocbpp + i))) {
 			ret = -EFAULT;
 			break;
 		}
 
-		if (unlikely(copy_from_user(&tmp, user_iocb, sizeof(tmp)))) {
-			ret = -EFAULT;
-			break;
-		}
-
-		ret = io_submit_one(ctx, user_iocb, &tmp, compat);
+		ret = io_submit_one(ctx, user_iocb, compat);
 		if (ret)
 			break;
 	}
-- 
2.11.0