vfs: make AIO use the proper rw_verify_area() area helpersandroid-wear-6.0.1_r0.78android-wear-6.0.1_r0.68android-bcm-tetra-3.10-marshmallow-mr1-wear-release

We had for some reason overlooked the AIO interface, and it didn't use
the proper rw_verify_area() helper function that checks (for example)
mandatory locking on the file, and that the size of the access doesn't
cause us to overflow the provided offset limits etc.

Instead, AIO did just the security_file_permission() thing (that
rw_verify_area() also does) directly.

This fixes it to do all the proper helper functions, which not only
means that now mandatory file locking works with AIO too, we can
actually remove lines of code.

Reported-by: Manish Honap <manish_honap_vit@yahoo.co.in>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
(cherry picked from commit a70b52ec1aaeaf60f4739edb1b422827cb6f3893)

Conflicts:
	fs/aio.c

Issue: KIONE-3528
Change-Id: I16f425d86e886a50b20fd397ce6f4f8cf1d60dd7

1 files changed, 21 insertions, 9 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 109e896c05a..4afba4bc33d 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -968,25 +968,37 @@ static ssize_t aio_setup_vectored_rw(int rw, struct kiocb *kiocb, bool compat)
 	if (ret < 0)
 		return ret;
 
-	/* ki_nbytes now reflect bytes instead of segs */
+	ret = rw_verify_area(rw, kiocb->ki_filp, &kiocb->ki_pos, ret);
+	if (ret < 0)
+		return ret;
+
+	kiocb->ki_nr_segs = kiocb->ki_nbytes;
+	kiocb->ki_cur_seg = 0;
+	/* ki_nbytes/left now reflect bytes instead of segs */
 	kiocb->ki_nbytes = ret;
-	return 0;
+	kiocb->ki_left = ret;
+	return ret;
 }
 
-static ssize_t aio_setup_single_vector(int rw, struct kiocb *kiocb)
+static ssize_t aio_setup_single_vector(int type, struct file * file, struct kiocb *kiocb)
 {
-	size_t len = kiocb->ki_nbytes;
+	int bytes;
+
+	bytes = rw_verify_area(type, file, &kiocb->ki_pos, kiocb->ki_left);
+	if (bytes < 0)
+		return bytes;
 
-	if (len > MAX_RW_COUNT)
-		len = MAX_RW_COUNT;
+	if (bytes > MAX_RW_COUNT)
+		bytes = MAX_RW_COUNT;
 
-	if (unlikely(!access_ok(!rw, kiocb->ki_buf, len)))
+	if (unlikely(!access_ok(!type, kiocb->ki_buf, bytes)))
                 return -EFAULT;
 
 	kiocb->ki_iovec = &kiocb->ki_inline_vec;
 	kiocb->ki_iovec->iov_base = kiocb->ki_buf;
-	kiocb->ki_iovec->iov_len = len;
+	kiocb->ki_iovec->iov_len = bytes;
 	kiocb->ki_nr_segs = 1;
+	kiocb->ki_cur_seg = 0;
 	return 0;
 }
 
@@ -1027,7 +1039,7 @@ rw_common:
 		ret = (req->ki_opcode == IOCB_CMD_PREADV ||
 		       req->ki_opcode == IOCB_CMD_PWRITEV)
 			? aio_setup_vectored_rw(rw, req, compat)
-			: aio_setup_single_vector(rw, req);
+		  : aio_setup_single_vector(rw, file, req);
 		if (ret)
 			return ret;