target/linux/brcm2708/patches-4.19/950-0687-Limit-max_req_size-under-arm64-or-any-other-platform.patch

   1 From 7bfcb31431f06efc233e4cc4d7ab65e10a6522cd Mon Sep 17 00:00:00 2001
   2 From: Yaroslav Rosomakho <yaroslavros@gmail.com>
   3 Date: Fri, 23 Aug 2019 11:02:22 +0200
   4 Subject: [PATCH] Limit max_req_size under arm64 (or any other platform
   5  that uses swiotlb) to prevent potential buffer overflow due to bouncing.
   6
   7 Signed-off-by: Yaroslav Rosomakho <yaroslavros@gmail.com>
   8 ---
   9  drivers/mmc/host/bcm2835-mmc.c | 6 +++++-
  10  1 file changed, 5 insertions(+), 1 deletion(-)
  11
  12 --- a/drivers/mmc/host/bcm2835-mmc.c
  13 +++ b/drivers/mmc/host/bcm2835-mmc.c
  14 @@ -38,6 +38,7 @@
  15  #include <linux/dmaengine.h>
  16  #include <linux/dma-mapping.h>
  17  #include <linux/of_dma.h>
  18 +#include <linux/swiotlb.h>
  19
  20  #include "sdhci.h"
  21
  22 @@ -1374,7 +1375,10 @@ static int bcm2835_mmc_add_host(struct b
  23         }
  24  #endif
  25         mmc->max_segs = 128;
  26 -       mmc->max_req_size = 524288;
  27 +       if (swiotlb_max_segment())
  28 +               mmc->max_req_size = (1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
  29 +       else
  30 +               mmc->max_req_size = 524288;
  31         mmc->max_seg_size = mmc->max_req_size;
  32         mmc->max_blk_size = 512;
  33         mmc->max_blk_count =  65535;