Commit fa63f083b349 for kernel

commit fa63f083b3492b5ed5332b8d7c90b03b5ef24a1d
Author: Souptick Joarder <jrdr.linux@gmail.com>
Date:   Thu Oct 15 20:13:15 2020 -0700

    rapidio: fix error handling path

    rio_dma_transfer() attempts to clamp the return value of
    pin_user_pages_fast() to be >= 0.  However, the attempt fails because
    nr_pages is overridden a few lines later, and restored to the undesirable
    -ERRNO value.

    The return value is ultimately stored in nr_pages, which in turn is passed
    to unpin_user_pages(), which expects nr_pages >= 0, else, disaster.

    Fix this by fixing the nesting of the assignment to nr_pages: nr_pages
    should be clamped to zero if pin_user_pages_fast() returns -ERRNO, or set
    to the return value of pin_user_pages_fast(), otherwise.

    [jhubbard@nvidia.com: new changelog]

    Fixes: e8de370188d09 ("rapidio: add mport char device driver")
    Signed-off-by: Souptick Joarder <jrdr.linux@gmail.com>
    Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
    Reviewed-by: Ira Weiny <ira.weiny@intel.com>
    Reviewed-by: John Hubbard <jhubbard@nvidia.com>
    Cc: Matthew Wilcox <willy@infradead.org>
    Cc: Matt Porter <mporter@kernel.crashing.org>
    Cc: Alexandre Bounine <alex.bou9@gmail.com>
    Cc: Gustavo A. R. Silva <gustavoars@kernel.org>
    Cc: Madhuparna Bhowmik <madhuparnabhowmik10@gmail.com>
    Cc: Dan Carpenter <dan.carpenter@oracle.com>
    Link: https://lkml.kernel.org/r/1600227737-20785-1-git-send-email-jrdr.linux@gmail.com
    Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
index a30342942e26..163b6c72501d 100644
--- a/drivers/rapidio/devices/rio_mport_cdev.c
+++ b/drivers/rapidio/devices/rio_mport_cdev.c
@@ -871,15 +871,16 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
 				rmcd_error("pin_user_pages_fast err=%ld",
 					   pinned);
 				nr_pages = 0;
-			} else
+			} else {
 				rmcd_error("pinned %ld out of %ld pages",
 					   pinned, nr_pages);
+				/*
+				 * Set nr_pages up to mean "how many pages to unpin, in
+				 * the error handler:
+				 */
+				nr_pages = pinned;
+			}
 			ret = -EFAULT;
-			/*
-			 * Set nr_pages up to mean "how many pages to unpin, in
-			 * the error handler:
-			 */
-			nr_pages = pinned;
 			goto err_pg;
 		}