Hi Sasha,
Thank you for the patch.
> -----Original Message-----
> From: Sasha Levin <sashal@xxxxxxxxxx>
> Sent: Thursday 18 June 2020 02:15
> To: linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx
> Cc: John Hubbard <jhubbard@xxxxxxxxxx>; Derek Kiernan <dkiernan@xxxxxxxxxx>; Dragan Cvetic <draganc@xxxxxxxxxx>; Arnd
> Bergmann <arnd@xxxxxxxx>; Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>; Michal Simek <michals@xxxxxxxxxx>; linux-arm-
> kernel@xxxxxxxxxxxxxxxxxxx; Sasha Levin <sashal@xxxxxxxxxx>
> Subject: [PATCH AUTOSEL 5.4 199/266] misc: xilinx-sdfec: improve get_user_pages_fast() error handling
>
> From: John Hubbard <jhubbard@xxxxxxxxxx>
>
> [ 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@xxxxxxxxxx>
> Cc: Dragan Cvetic <dragan.cvetic@xxxxxxxxxx>
> Cc: Arnd Bergmann <arnd@xxxxxxxx>
> Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Cc: Michal Simek <michal.simek@xxxxxxxxxx>
> Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
> Signed-off-by: John Hubbard <jhubbard@xxxxxxxxxx>
> Link: https://lore.kernel.org/r/20200527012628.1100649-2-jhubbard@xxxxxxxxxx
> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
> ---
> 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 48ba7e02bed7..d4c14b617201 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
Acked-by: Dragan Cvetic <dragan.cvetic@xxxxxxxxxx>
Regards
Dragan
