[PATCH] mtd: parser: cmdline: Fix parsing of part-names with colons

[PATCH] mtd: parser: cmdline: Fix parsing of part-names with colons

[Sven Eckelmann]

Some devices (especially QCA ones) are already using hardcoded partition
names with colons in it. The OpenMesh A62 for example provides following
mtd relevant information via cmdline:

  root=31:11 mtdparts=spi0.0:256k(0:SBL1),128k(0:MIBIB),384k(0:QSEE),64k(0:CDT),64k(0:DDRPARAMS),64k(0:APPSBLENV),512k(0:APPSBL),64k(0:ART),64k(custom),64k(0:KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive) rootfsname=rootfs rootwait

The change to split only on the last colon between mtd-id and partitions
will cause newpart to see following string for the first partition:

  KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)

Such a partition list cannot be parsed and thus the device fails to boot.

Avoid this behavior by making sure that the start of the first part-name
("(") will also be the last byte the mtd-id split algorithm is using for
its colon search.

Fixes: eb13fa022741 ("mtd: parser: cmdline: Support MTD names containing one or more colons")
Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
 drivers/mtd/parsers/cmdlinepart.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/parsers/cmdlinepart.c b/drivers/mtd/parsers/cmdlinepart.c
index a79e4d866b08..655c6d59bd05 100644
--- a/drivers/mtd/parsers/cmdlinepart.c
+++ b/drivers/mtd/parsers/cmdlinepart.c
@@ -226,7 +226,7 @@ static int mtdpart_setup_real(char *s)
 		struct cmdline_mtd_partition *this_mtd;
 		struct mtd_partition *parts;
 		int mtd_id_len, num_parts;
-		char *p, *mtd_id, *semicol;
+		char *p, *mtd_id, *semicol, *open_parenth;
 
 		/*
 		 * Replace the first ';' by a NULL char so strrchr can work
@@ -236,6 +236,13 @@ static int mtdpart_setup_real(char *s)
 		if (semicol)
 			*semicol = '\0';
 
+		/* make sure that part-names with ":" will not be handled as
+		 * part of the mtd-id with an ":"
+		 */
+		open_parenth = strchr(s, '(');
+		if (open_parenth)
+			*open_parenth = '\0';
+
 		mtd_id = s;
 
 		/*
@@ -245,6 +252,10 @@ static int mtdpart_setup_real(char *s)
 		 */
 		p = strrchr(s, ':');
 
+		/* Restore the '(' now. */
+		if (open_parenth)
+			*open_parenth = '(';
+
 		/* Restore the ';' now. */
 		if (semicol)
 			*semicol = ';';
-- 
2.29.2


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Re: [PATCH] mtd: parser: cmdline: Fix parsing of part-names with colons

[Miquel Raynal]

Hi Sven,

Sven Eckelmann <sven@narfation.org> wrote on Sun, 22 Nov 2020 01:15:33
+0100:

> Some devices (especially QCA ones) are already using hardcoded partition
> names with colons in it. The OpenMesh A62 for example provides following
> mtd relevant information via cmdline:
> 
>   root=31:11 mtdparts=spi0.0:256k(0:SBL1),128k(0:MIBIB),384k(0:QSEE),64k(0:CDT),64k(0:DDRPARAMS),64k(0:APPSBLENV),512k(0:APPSBL),64k(0:ART),64k(custom),64k(0:KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive) rootfsname=rootfs rootwait
> 
> The change to split only on the last colon between mtd-id and partitions
> will cause newpart to see following string for the first partition:
> 
>   KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)
> 
> Such a partition list cannot be parsed and thus the device fails to boot.
> 
> Avoid this behavior by making sure that the start of the first part-name
> ("(") will also be the last byte the mtd-id split algorithm is using for
> its colon search.

Nice.

Ron, can you give this patch a shot and answer with your Tested-by: to
this thread if it still works for you? 

> Fixes: eb13fa022741 ("mtd: parser: cmdline: Support MTD names containing one or more colons")
> Signed-off-by: Sven Eckelmann <sven@narfation.org>
> ---
>  drivers/mtd/parsers/cmdlinepart.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mtd/parsers/cmdlinepart.c b/drivers/mtd/parsers/cmdlinepart.c
> index a79e4d866b08..655c6d59bd05 100644
> --- a/drivers/mtd/parsers/cmdlinepart.c
> +++ b/drivers/mtd/parsers/cmdlinepart.c
> @@ -226,7 +226,7 @@ static int mtdpart_setup_real(char *s)
>  		struct cmdline_mtd_partition *this_mtd;
>  		struct mtd_partition *parts;
>  		int mtd_id_len, num_parts;
> -		char *p, *mtd_id, *semicol;
> +		char *p, *mtd_id, *semicol, *open_parenth;
>  
>  		/*
>  		 * Replace the first ';' by a NULL char so strrchr can work
> @@ -236,6 +236,13 @@ static int mtdpart_setup_real(char *s)
>  		if (semicol)
>  			*semicol = '\0';
>  
> +		/* make sure that part-names with ":" will not be handled as
> +		 * part of the mtd-id with an ":"

We prefer this style of multiline comment in MTD:

	/*
	 * Something.
	 * Something else.
	 */

> +		 */
> +		open_parenth = strchr(s, '(');
> +		if (open_parenth)
> +			*open_parenth = '\0';
> +
>  		mtd_id = s;
>  
>  		/*
> @@ -245,6 +252,10 @@ static int mtdpart_setup_real(char *s)
>  		 */
>  		p = strrchr(s, ':');
>  
> +		/* Restore the '(' now. */
> +		if (open_parenth)
> +			*open_parenth = '(';
> +
>  		/* Restore the ';' now. */
>  		if (semicol)
>  			*semicol = ';';

Otherwise LGTM.

Thanks,
Miquèl

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Re: [PATCH] mtd: parser: cmdline: Fix parsing of part-names with colons

[Boris Brezillon]

On Mon, 23 Nov 2020 09:38:14 +0100
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Hi Sven,
> 
> Sven Eckelmann <sven@narfation.org> wrote on Sun, 22 Nov 2020 01:15:33
> +0100:
> 
> > Some devices (especially QCA ones) are already using hardcoded partition
> > names with colons in it. The OpenMesh A62 for example provides following
> > mtd relevant information via cmdline:
> > 
> >   root=31:11 mtdparts=spi0.0:256k(0:SBL1),128k(0:MIBIB),384k(0:QSEE),64k(0:CDT),64k(0:DDRPARAMS),64k(0:APPSBLENV),512k(0:APPSBL),64k(0:ART),64k(custom),64k(0:KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive) rootfsname=rootfs rootwait
> > 
> > The change to split only on the last colon between mtd-id and partitions
> > will cause newpart to see following string for the first partition:
> > 
> >   KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)
> > 
> > Such a partition list cannot be parsed and thus the device fails to boot.
> > 
> > Avoid this behavior by making sure that the start of the first part-name
> > ("(") will also be the last byte the mtd-id split algorithm is using for
> > its colon search.  

Sounds reasonable to me. Note that it works until people start using
parens in their MTD name, so let's hope nobody does that :D. We should
really rework the mtdpart parsing code to make it more robust (do
context based parsing instead of this simple 'strchr()' solution).

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