RE: [PATCH AUTOSEL 5.4 199/266] misc: xilinx-sdfec: improve get_user_pages_fast() error handling

Hi Sasha,

Thank you for the patch.

-----Original Message----- From: Sasha Levin sashal@kernel.org Sent: Thursday 18 June 2020 02:15 To: linux-kernel@vger.kernel.org; stable@vger.kernel.org Cc: John Hubbard jhubbard@nvidia.com; Derek Kiernan dkiernan@xilinx.com; Dragan Cvetic draganc@xilinx.com; Arnd Bergmann arnd@arndb.de; Greg Kroah-Hartman gregkh@linuxfoundation.org; Michal Simek michals@xilinx.com; linux-arm- kernel@lists.infradead.org; Sasha Levin sashal@kernel.org Subject: [PATCH AUTOSEL 5.4 199/266] misc: xilinx-sdfec: improve get_user_pages_fast() error handling

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 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@xilinx.com

Regards Dragan