[PATCH 2/2] mmc core block.c: avoid negative index with array access

[mikko.rapeli@linaro.org]

From: Mikko Rapeli <mikko.rapeli@linaro.org>

Commit "mmc: core: Use mrq.sbc in close-ended ffu" assigns
prev_idata = idatas[i - 1] but doesn't check that int iterator
i is greater than zero. Add the check.

Fixes: 4d0c8d0aef63 ("mmc: core: Use mrq.sbc in close-ended ffu")

Link: https://lore.kernel.org/all/20231129092535.3278-1-avri.altman@wdc.com/

Cc: Avri Altman <avri.altman@wdc.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: linux-mmc@vger.kernel.org
Cc: stable@vger.kernel.org
Signed-off-by: Mikko Rapeli <mikko.rapeli@linaro.org>
---
 drivers/mmc/core/block.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
index 0df627de9cee..7f275b4ca9fa 100644
--- a/drivers/mmc/core/block.c
+++ b/drivers/mmc/core/block.c
@@ -488,7 +488,7 @@ static int __mmc_blk_ioctl_cmd(struct mmc_card *card, struct mmc_blk_data *md,
 	if (idata->flags & MMC_BLK_IOC_DROP)
 		return 0;
 
-	if (idata->flags & MMC_BLK_IOC_SBC)
+	if (idata->flags & MMC_BLK_IOC_SBC && i > 0)
 		prev_idata = idatas[i - 1];
 
 	/*
-- 
2.34.1