From 54841ab50c20d6fa6c9cc3eb826989da3a22d934 Mon Sep 17 00:00:00 2001
From: Wolfgang Denk <wd@denx.de>
Date: Mon, 28 Jun 2010 22:00:46 +0200
Subject: Make sure that argv[] argument pointers are not modified.

The hush shell dynamically allocates (and re-allocates) memory for the
argument strings in the "char *argv[]" argument vector passed to
commands.  Any code that modifies these pointers will cause serious
corruption of the malloc data structures and crash U-Boot, so make
sure the compiler can check that no such modifications are being done
by changing the code into "char * const argv[]".

This modification is the result of debugging a strange crash caused
after adding a new command, which used the following argument
processing code which has been working perfectly fine in all Unix
systems since version 6 - but not so in U-Boot:

int main (int argc, char **argv)
{
	while (--argc > 0 && **++argv == '-') {
/* ====> */	while (*++*argv) {
			switch (**argv) {
			case 'd':
				debug++;
				break;
			...
			default:
				usage ();
			}
		}
	}
	...
}

The line marked "====>" will corrupt the malloc data structures and
usually cause U-Boot to crash when the next command gets executed by
the shell.  With the modification, the compiler will prevent this with
an
	error: increment of read-only location '*argv'

N.B.: The code above can be trivially rewritten like this:

	while (--argc > 0 && **++argv == '-') {
		char *arg = *argv;
		while (*++arg) {
			switch (*arg) {
			...

Signed-off-by: Wolfgang Denk <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
---
 board/g2000/g2000.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

(limited to 'board/g2000/g2000.c')

diff --git a/board/g2000/g2000.c b/board/g2000/g2000.c
index 03cd6b8..8b15e51 100644
--- a/board/g2000/g2000.c
+++ b/board/g2000/g2000.c
@@ -148,7 +148,7 @@ phys_size_t initdram (int board_type)
 }
 
 #if 0 /* test-only !!! */
-int do_dumpebc(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_dumpebc(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong ap, cr;
 
@@ -174,7 +174,7 @@ U_BOOT_CMD(
 );
 
 
-int do_dumpdcr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_dumpdcr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;
 
@@ -196,7 +196,7 @@ U_BOOT_CMD(
 );
 
 
-int do_dumpspr(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_dumpspr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	printf("\nSpecial Purpose Registers (SPR's) for PPC405GP:");
 	printf("\n%04x %08x ", 947, mfspr(947));
-- 
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