[PATCH 4.4 124/132] mtd: parser: cmdline: Fix parsing of part-names with colons

[Greg Kroah-Hartman]

From: Sven Eckelmann <sven@xxxxxxxxxxxxx>

commit 639a82434f16a6df0ce0e7c8595976f1293940fd upstream.

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")
Cc: stable@xxxxxxxxxxxxxxx
Cc: Ron Minnich <rminnich@xxxxxxxxxx>
Signed-off-by: Sven Eckelmann <sven@xxxxxxxxxxxxx>
Signed-off-by: Miquel Raynal <miquel.raynal@xxxxxxxxxxx>
Link: https://lore.kernel.org/linux-mtd/20201124062506.185392-1-sven@xxxxxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
 drivers/mtd/cmdlinepart.c |   14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

--- a/drivers/mtd/cmdlinepart.c
+++ b/drivers/mtd/cmdlinepart.c
@@ -228,7 +228,7 @@ 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
@@ -238,6 +238,14 @@ 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;
 
 		/*
@@ -247,6 +255,10 @@ static int mtdpart_setup_real(char *s)
 		 */
 		p = strrchr(s, ':');
 
+		/* Restore the '(' now. */
+		if (open_parenth)
+			*open_parenth = '(';
+
 		/* Restore the ';' now. */
 		if (semicol)
 			*semicol = ';';