dmaengine: imx-sdma: fix size check for sdma script_number

Illegal memory will be touch if SDMA_SCRIPT_ADDRS_ARRAY_SIZE_V3
(41) exceed the size of structure sdma_script_start_addrs(40),
thus cause memory corrupt such as slob block header so that kernel
trap into while() loop forever in slob_free(). Please refer to below
code piece in imx-sdma.c:
for (i = 0; i < sdma->script_number; i++)
	if (addr_arr[i] > 0)
		saddr_arr[i] = addr_arr[i]; /* memory corrupt here */
That issue was brought by commit a572460 ("dmaengine: imx-sdma: Add
support for version 3 firmware") because SDMA_SCRIPT_ADDRS_ARRAY_SIZE_V3
(38->41 3 scripts added) not align with script number added in
sdma_script_start_addrs(2 scripts).

Fixes: a572460 ("dmaengine: imx-sdma: Add support for version 3 firmware")
Cc: stable@vger.kernel
Link: https://www.spinics.net/lists/arm-kernel/msg754895.html
Signed-off-by: Robin Gong <yibin.gong@nxp.com>
Reported-by: Jurgen Lambrecht <J.Lambrecht@TELEVIC.com>
Link: https://lore.kernel.org/r/1569347584-3478-1-git-send-email-yibin.gong@nxp.com
[vkoul: update the patch title]
Signed-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/imx-sdma.c

@@ -1707,6 +1707,14 @@ static void sdma_add_scripts(struct sdma_engine *sdma,
 	if (!sdma->script_number)
 		sdma->script_number = SDMA_SCRIPT_ADDRS_ARRAY_SIZE_V1;
 
+	if (sdma->script_number > sizeof(struct sdma_script_start_addrs)
+				  / sizeof(s32)) {
+		dev_err(sdma->dev,
+			"SDMA script number %d not match with firmware.\n",
+			sdma->script_number);
+		return;
+	}
+
 	for (i = 0; i < sdma->script_number; i++)
 		if (addr_arr[i] > 0)
 			saddr_arr[i] = addr_arr[i];

include/linux/platform_data/dma-imx-sdma.h

@@ -51,7 +51,10 @@ struct sdma_script_start_addrs {
 	/* End of v2 array */
 	s32 zcanfd_2_mcu_addr;
 	s32 zqspi_2_mcu_addr;
+	s32 mcu_2_ecspi_addr;
 	/* End of v3 array */
+	s32 mcu_2_zqspi_addr;
+	/* End of v4 array */
 };
 
 /**