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mmc: sdhci: Fix potential ADMA descriptor table overflow

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Change ADMA_TABLE_NO_ENTRIES to round the division up to fully
contain CONFIG_SYS_MMC_MAX_BLK_COUNT, fixing potential buffer overflow
of the ADMA descriptor table.

sdhci_prepare_adma_table() expecitily states it does _not_ check for
overflow as the descriptor table size is dependent on
CONFIG_SYS_MMC_MAX_BLK_COUNT. However, the ADMA_TABLE_NO_ENTRIES
calculation does not round up the divison, so with the current u-boot
 defaults:
max_mmc_transfer = (CONFIG_SYS_MMC_MAX_BLK_COUNT * MMC_MAX_BLOCK_LEN) =
65535 * 512 = 33553920 bytes.
ADMA_TABLE_NO_ENTRIES = max_mmc_transfer / ADMA_MAX_LEN =
33553920 / 65532, which does not divide cleanly.
actual_max_transfer = ADMA_TABLE_NO_ENTRIES * ADMA_MAX_LEN = 512 *
65532 = 33552384, which is smaller than max_mmc_transfer.
This can cause sdhci_prepare_adma_table() to write one extra
descriptor, overflowing the table when a transaction larger than
actual_max_transfer is issued.

Co-developed-by: Nathan Barrett-Morrison <nathan.morrison@timesys.com>
Signed-off-by: Nathan Barrett-Morrison <nathan.morrison@timesys.com>
Signed-off-by: Greg Malysa <greg.malysa@timesys.com>
Signed-off-by: Ian Roberts <ian.roberts@timesys.com>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
This commit is contained in:
Ian Roberts 2024-03-25 22:22:37 -04:00 • committed by Jaehoon Chung
parent 74755c1fed
commit 5f07144968
1 changed files with 3 additions and 2 deletions
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5
include/sdhci.h
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@ -11,6 +11,7 @@
#include <linux/bitops.h>
#include <linux/types.h>
#include <linux/kernel.h>
#include <asm/io.h>
#include <mmc.h>
#include <asm/gpio.h>
@ -304,8 +305,8 @@ struct sdhci_ops {
#else
#define ADMA_DESC_LEN 8
#endif
#define ADMA_TABLE_NO_ENTRIES (CONFIG_SYS_MMC_MAX_BLK_COUNT * \
MMC_MAX_BLOCK_LEN) / ADMA_MAX_LEN
#define ADMA_TABLE_NO_ENTRIES DIV_ROUND_UP(CONFIG_SYS_MMC_MAX_BLK_COUNT * \
MMC_MAX_BLOCK_LEN, ADMA_MAX_LEN)
#define ADMA_TABLE_SZ (ADMA_TABLE_NO_ENTRIES * ADMA_DESC_LEN)