Re: [PATCH][v3] mtd: rawnand: fsl_ifc: Fix eccstat array overflow for IFC ver >= 2.0.0

Re: [PATCH][v3] mtd: rawnand: fsl_ifc: Fix eccstat array overflow for IFC ver >= 2.0.0

[Boris Brezillon]

On Tue, 20 Mar 2018 21:37:39 +0530
Jagdish Gediya <jagdish.gediya@nxp.com> wrote:

> Number of ECC status registers i.e. (ECCSTATx) has been increased in IFC
> version 2.0.0 due to increase in SRAM size. This is causing eccstat
> array to over flow.
> 
> So, replace eccstat array with u32 variable to make it fail-safe and
> independent of number of ECC status registers or SRAM size.
> 
> Fixes: bccb06c353af ("mtd: nand: ifc: update bufnum mask for ver >= 2.0.0")
> Cc: stable@vger.kernel.org # 3.18+
> Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
> Signed-off-by: Jagdish Gediya <jagdish.gediya@nxp.com>
> ---
> Changes for v2: Incorporated comments from Miquel Raynal and Boris Brezillon 
> 	- Updated patch subject
> 	- Remove usage of eccstat array
> 	- Added Cc: stable@vger.kernel.org 
> 
> Changes for v3: Incorporated comments from Boris Brezillon
> 	- Added fixes tag
> 
>  drivers/mtd/nand/fsl_ifc_nand.c | 23 +++++++++++++----------
>  1 file changed, 13 insertions(+), 10 deletions(-)
> 
> diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
> index 4872a7b..9390cbd 100644
> --- a/drivers/mtd/nand/fsl_ifc_nand.c
> +++ b/drivers/mtd/nand/fsl_ifc_nand.c
> @@ -173,14 +173,9 @@ static void set_addr(struct mtd_info *mtd, int column, int page_addr, int oob)
>  
>  /* returns nonzero if entire page is blank */
>  static int check_read_ecc(struct mtd_info *mtd, struct fsl_ifc_ctrl *ctrl,
> -			  u32 *eccstat, unsigned int bufnum)
> +			  u32 eccstat, unsigned int bufnum)
>  {
> -	u32 reg = eccstat[bufnum / 4];
> -	int errors;
> -
> -	errors = (reg >> ((3 - bufnum % 4) * 8)) & 15;
> -
> -	return errors;
> +	return  (eccstat >> ((3 - bufnum % 4) * 8)) & 15;
>  }
>  
>  /*
> @@ -193,7 +188,7 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
>  	struct fsl_ifc_ctrl *ctrl = priv->ctrl;
>  	struct fsl_ifc_nand_ctrl *nctrl = ifc_nand_ctrl;
>  	struct fsl_ifc_runtime __iomem *ifc = ctrl->rregs;
> -	u32 eccstat[4];
> +	u32 eccstat;
>  	int i;
>  
>  	/* set the chip select for NAND Transaction */
> @@ -237,10 +232,18 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
>  		else
>  			eccstat_regs = ifc->ifc_nand.v1_nand_eccstat;
>  
> -		for (i = sector / 4; i <= sector_end / 4; i++)
> -			eccstat[i] = ifc_in32(&eccstat_regs[i]);
> +		eccstat = 0;

I guess you do that because gcc complains about an uninitialized var.
How about initializing eccstat correctly here:

		eccstat = ifc_in32(&eccstat_regs[sector / 4]);

>  
>  		for (i = sector; i <= sector_end; i++) {
> +

Remove this empty line.

> +			/*
> +			 * sector is not necessarily aligned on 4 and
> +			 * we need to read the eccstat in this case,
> +			 * hence the sector test.
> +			 */
> +			if ((i % 4 == 0) || (sector == sector_end))

I still think the sector == sector_end test is less clear than an i ==
sector (which BTW should be named sector_start to clarify things).

Anyway, if you initialize eccstat as suggested above, here you should
have:

			if (i != sector && !(i % 4))
				eccstat = ifc_in32(&eccstat_regs[i / 4]);

> +				eccstat = ifc_in32(&eccstat_regs[i / 4]);
> +
>  			errors = check_read_ecc(mtd, ctrl, eccstat, i);
>  
>  			if (errors == 15) {



-- 
Boris Brezillon, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
https://bootlin.com

[PATCH][v3] mtd: rawnand: fsl_ifc: Fix eccstat array overflow for IFC ver >= 2.0.0

[Jagdish Gediya]

Number of ECC status registers i.e. (ECCSTATx) has been increased in IFC
version 2.0.0 due to increase in SRAM size. This is causing eccstat
array to over flow.

So, replace eccstat array with u32 variable to make it fail-safe and
independent of number of ECC status registers or SRAM size.

Fixes: bccb06c353af ("mtd: nand: ifc: update bufnum mask for ver >= 2.0.0")
Cc: stable@vger.kernel.org # 3.18+
Signed-off-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>
Signed-off-by: Jagdish Gediya <jagdish.gediya@nxp.com>
---
Changes for v2: Incorporated comments from Miquel Raynal and Boris Brezillon 
	- Updated patch subject
	- Remove usage of eccstat array
	- Added Cc: stable@vger.kernel.org 

Changes for v3: Incorporated comments from Boris Brezillon
	- Added fixes tag

 drivers/mtd/nand/fsl_ifc_nand.c | 23 +++++++++++++----------
 1 file changed, 13 insertions(+), 10 deletions(-)

diff --git a/drivers/mtd/nand/fsl_ifc_nand.c b/drivers/mtd/nand/fsl_ifc_nand.c
index 4872a7b..9390cbd 100644
--- a/drivers/mtd/nand/fsl_ifc_nand.c
+++ b/drivers/mtd/nand/fsl_ifc_nand.c
@@ -173,14 +173,9 @@ static void set_addr(struct mtd_info *mtd, int column, int page_addr, int oob)
 
 /* returns nonzero if entire page is blank */
 static int check_read_ecc(struct mtd_info *mtd, struct fsl_ifc_ctrl *ctrl,
-			  u32 *eccstat, unsigned int bufnum)
+			  u32 eccstat, unsigned int bufnum)
 {
-	u32 reg = eccstat[bufnum / 4];
-	int errors;
-
-	errors = (reg >> ((3 - bufnum % 4) * 8)) & 15;
-
-	return errors;
+	return  (eccstat >> ((3 - bufnum % 4) * 8)) & 15;
 }
 
 /*
@@ -193,7 +188,7 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
 	struct fsl_ifc_ctrl *ctrl = priv->ctrl;
 	struct fsl_ifc_nand_ctrl *nctrl = ifc_nand_ctrl;
 	struct fsl_ifc_runtime __iomem *ifc = ctrl->rregs;
-	u32 eccstat[4];
+	u32 eccstat;
 	int i;
 
 	/* set the chip select for NAND Transaction */
@@ -237,10 +232,18 @@ static void fsl_ifc_run_command(struct mtd_info *mtd)
 		else
 			eccstat_regs = ifc->ifc_nand.v1_nand_eccstat;
 
-		for (i = sector / 4; i <= sector_end / 4; i++)
-			eccstat[i] = ifc_in32(&eccstat_regs[i]);
+		eccstat = 0;
 
 		for (i = sector; i <= sector_end; i++) {
+
+			/*
+			 * sector is not necessarily aligned on 4 and
+			 * we need to read the eccstat in this case,
+			 * hence the sector test.
+			 */
+			if ((i % 4 == 0) || (sector == sector_end))
+				eccstat = ifc_in32(&eccstat_regs[i / 4]);
+
 			errors = check_read_ecc(mtd, ctrl, eccstat, i);
 
 			if (errors == 15) {
-- 
1.9.1