Re: [PATCH] mtd: parser: cmdline: Support MTD names containing one or more colons

[Sven Eckelmann <sven@narfation.org>]

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On Wednesday, 29 April 2020 18:53:47 CET Ronald G. Minnich wrote:
> From: Boris Brezillon <boris.brezillon@collabora.com>
> 
> Looks like some drivers define MTD names with a colon in it, thus
> making mtdpart= parsing impossible. Let's fix the parser to gracefully
> handle that case: the last ':' in a partition definition sequence is
> considered instead of the first one.
> 
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> Signed-off-by: Ron Minnich <rminnich@google.com>
> Tested-by: Ron Minnich <rminnich@google.com>
> ---
>  drivers/mtd/parsers/cmdlinepart.c | 23 ++++++++++++++++++++---
>  1 file changed, 20 insertions(+), 3 deletions(-)

This change broke OpenWrt booting on some IPQ40xx devices. Here for example 
the parts of the cmdline which the u-boot on an OpenMesh A62 sets 
automatically:

    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

This is then parsed by newpart as: KEYS),0x002b0000(kernel),0x00c80000(rootfs),15552k(inactive)

And of course, this results in:

    mtd: partition has size 0
    [...]
    /dev/root: Can't open blockdev
    VFS: Cannot open root device "31:11" or unknown-block(31,11): error -6
    Please append a correct "root=" boot option; here are the available partitions:
    1f00           32768 mtdblock0
    (driver?)
    Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(31,11)
    CPU1: stopping
    CPU: 1 PID: 0 Comm: 

This affects OpenWrt since the commit d6a9a92e3217 ("kernel: bump 5.4 to 
5.4.69") because this change was backported to Linux v5.4.69. Reverting 
this change fixes the problem for me.

And if I see it correctly, this is also affecting the kernel (4.14) for
the OpenWrt 18.06.x + 19.07.x branch because it can also be found in
there as part of the v4.14.200 release.

Another workaround is to replace the first "(" with a NULL too. See the
attached patch for the one which I used to fix the OpenWrt bootup.

Kind regards,
	Sven

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From: Sven Eckelmann <sven@narfation.org>
Date: Sun, 22 Nov 2020 00:48:33 +0100
Subject: [PATCH RFC] mtd: parser: cmdline: Fix parsing of part-names with colons

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 colon search algorithm is using for
its mtd-id search.

Fixes: eb13fa022741 ("mtd: parser: cmdline: Support MTD names containing one or more colons")
Signed-off-by: Sven Eckelmann <sven@narfation.org>

diff --git a/drivers/mtd/parsers/cmdlinepart.c b/drivers/mtd/parsers/cmdlinepart.c
index 0625b25620ca766318ea4646a6e3761ff4d3a4cc..22881ea4c132ea5a5ba7aebd025d91bf1cd023af 100644
--- a/drivers/mtd/parsers/cmdlinepart.c
+++ b/drivers/mtd/parsers/cmdlinepart.c
@@ -218,7 +218,7 @@ 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
@@ -228,6 +228,13 @@ 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;
 
 		/*
@@ -237,6 +244,10 @@ static int mtdpart_setup_real(char *s)
 		 */
 		p = strrchr(s, ':');
 
+		/* Restore the '(' now. */
+		if (open_parenth)
+			*open_parenth = '(';
+
 		/* Restore the ';' now. */
 		if (semicol)
 			*semicol = ';';

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