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    Subject[PATCH 5.7 287/477] misc: xilinx-sdfec: improve get_user_pages_fast() error handling
    Date
    From: John Hubbard <jhubbard@nvidia.com>

    [ Upstream commit 57343d51613227373759f5b0f2eede257fd4b82e ]

    This fixes the case of get_user_pages_fast() returning a -errno.
    The result needs to be stored in a signed integer. And for safe
    signed/unsigned comparisons, it's best to keep everything signed.
    And get_user_pages_fast() also expects a signed value for number
    of pages to pin.

    Therefore, change most relevant variables, from u32 to int. Leave
    "n" unsigned, for convenience in checking for overflow. And provide
    a WARN_ON_ONCE() and early return, if overflow occurs.

    Also, as long as we're tidying up: rename the page array from page,
    to pages, in order to match the conventions used in most other call
    sites.

    Fixes: 20ec628e8007e ("misc: xilinx_sdfec: Add ability to configure LDPC")
    Cc: Derek Kiernan <derek.kiernan@xilinx.com>
    Cc: Dragan Cvetic <dragan.cvetic@xilinx.com>
    Cc: Arnd Bergmann <arnd@arndb.de>
    Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Cc: Michal Simek <michal.simek@xilinx.com>
    Cc: linux-arm-kernel@lists.infradead.org
    Signed-off-by: John Hubbard <jhubbard@nvidia.com>
    Link: https://lore.kernel.org/r/20200527012628.1100649-2-jhubbard@nvidia.com
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/misc/xilinx_sdfec.c | 27 +++++++++++++++++----------
    1 file changed, 17 insertions(+), 10 deletions(-)

    diff --git a/drivers/misc/xilinx_sdfec.c b/drivers/misc/xilinx_sdfec.c
    index 71bbaa56bdb5b..e2766aad9e142 100644
    --- a/drivers/misc/xilinx_sdfec.c
    +++ b/drivers/misc/xilinx_sdfec.c
    @@ -602,10 +602,10 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset,
    const u32 depth)
    {
    u32 reg = 0;
    - u32 res;
    - u32 n, i;
    + int res, i, nr_pages;
    + u32 n;
    u32 *addr = NULL;
    - struct page *page[MAX_NUM_PAGES];
    + struct page *pages[MAX_NUM_PAGES];

    /*
    * Writes that go beyond the length of
    @@ -622,15 +622,22 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset,
    if ((len * XSDFEC_REG_WIDTH_JUMP) % PAGE_SIZE)
    n += 1;

    - res = get_user_pages_fast((unsigned long)src_ptr, n, 0, page);
    - if (res < n) {
    - for (i = 0; i < res; i++)
    - put_page(page[i]);
    + if (WARN_ON_ONCE(n > INT_MAX))
    + return -EINVAL;
    +
    + nr_pages = n;
    +
    + res = get_user_pages_fast((unsigned long)src_ptr, nr_pages, 0, pages);
    + if (res < nr_pages) {
    + if (res > 0) {
    + for (i = 0; i < res; i++)
    + put_page(pages[i]);
    + }
    return -EINVAL;
    }

    - for (i = 0; i < n; i++) {
    - addr = kmap(page[i]);
    + for (i = 0; i < nr_pages; i++) {
    + addr = kmap(pages[i]);
    do {
    xsdfec_regwrite(xsdfec,
    base_addr + ((offset + reg) *
    @@ -639,7 +646,7 @@ static int xsdfec_table_write(struct xsdfec_dev *xsdfec, u32 offset,
    reg++;
    } while ((reg < len) &&
    ((reg * XSDFEC_REG_WIDTH_JUMP) % PAGE_SIZE));
    - put_page(page[i]);
    + put_page(pages[i]);
    }
    return reg;
    }
    --
    2.25.1


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