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    Subject[PATCH 4.9 076/139] rapidio: fix error handling path
    Date
    From: Souptick Joarder <jrdr.linux@gmail.com>

    [ Upstream commit fa63f083b3492b5ed5332b8d7c90b03b5ef24a1d ]

    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>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/rapidio/devices/rio_mport_cdev.c | 13 +++++++------
    1 file changed, 7 insertions(+), 6 deletions(-)

    diff --git a/drivers/rapidio/devices/rio_mport_cdev.c b/drivers/rapidio/devices/rio_mport_cdev.c
    index ebe8e8dc46770..21d0dd1617e27 100644
    --- a/drivers/rapidio/devices/rio_mport_cdev.c
    +++ b/drivers/rapidio/devices/rio_mport_cdev.c
    @@ -901,15 +901,16 @@ rio_dma_transfer(struct file *filp, u32 transfer_mode,
    if (pinned < 0) {
    rmcd_error("get_user_pages 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;
    }

    --
    2.25.1


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