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>

2 files changed, 3 insertions, 3 deletions

diff --git a/arch/microblaze/cpu/interrupts.c b/arch/microblaze/cpu/interrupts.c
index 7a9d022eee..e9d53c1afd 100644
--- a/arch/microblaze/cpu/interrupts.c
+++ b/arch/microblaze/cpu/interrupts.c
@@ -173,7 +173,7 @@ void interrupt_handler (void)
 
 #if defined(CONFIG_CMD_IRQ)
 #ifdef CONFIG_SYS_INTC_0
-int do_irqinfo (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_irqinfo (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	int i;
 	struct irq_action *act = vecs;
@@ -193,7 +193,7 @@ int do_irqinfo (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
 	return (0);
 }
 #else
-int do_irqinfo (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_irqinfo (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	puts ("Undefined interrupt controller\n");
 }
diff --git a/arch/microblaze/lib/bootm.c b/arch/microblaze/lib/bootm.c
index 2227a81bb0..8e2c6d8922 100644
--- a/arch/microblaze/lib/bootm.c
+++ b/arch/microblaze/lib/bootm.c
@@ -32,7 +32,7 @@
 
 DECLARE_GLOBAL_DATA_PTR;
 
-int do_bootm_linux(int flag, int argc, char *argv[], bootm_headers_t *images)
+int do_bootm_linux(int flag, int argc, char * const argv[], bootm_headers_t *images)
 {
 	/* First parameter is mapped to $r5 for kernel boot args */
 	void	(*theKernel) (char *, ulong, ulong);