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From ea1ecb2257bef3cc0b23c08364436103141999c7 Mon Sep 17 00:00:00 2001
From: Yaroslav Rosomakho <yaroslavros@gmail.com>
Date: Fri, 23 Aug 2019 11:02:22 +0200
Subject: [PATCH 2/2] Limit max_req_size under arm64 (or any other platform
that uses swiotlb) to prevent potential buffer overflow due to bouncing.
Signed-off-by: Yaroslav Rosomakho <yaroslavros@gmail.com>
---
drivers/mmc/host/bcm2835-mmc.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
--- a/drivers/mmc/host/bcm2835-mmc.c
+++ b/drivers/mmc/host/bcm2835-mmc.c
@@ -38,6 +38,7 @@
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/of_dma.h>
+#include <linux/swiotlb.h>
#include "sdhci.h"
@@ -1377,7 +1378,10 @@ static int bcm2835_mmc_add_host(struct b
}
#endif
mmc->max_segs = 128;
- mmc->max_req_size = 524288;
+ if (swiotlb_max_segment())
+ mmc->max_req_size = (1 << IO_TLB_SHIFT) * IO_TLB_SEGSIZE;
+ else
+ mmc->max_req_size = 524288;
mmc->max_seg_size = mmc->max_req_size;
mmc->max_blk_size = 512;
mmc->max_blk_count = 65535;
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