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>

1 files changed, 3 insertions, 3 deletions

diff --git a/common/cmd_fdt.c b/common/cmd_fdt.c
index 5df79ae3e..cd4c6de6d 100644
--- a/common/cmd_fdt.c
+++ b/common/cmd_fdt.c
@@ -42,7 +42,7 @@
 DECLARE_GLOBAL_DATA_PTR;
 
 static int fdt_valid(void);
-static int fdt_parse_prop(char **newval, int count, char *data, int *len);
+static int fdt_parse_prop(char *const*newval, int count, char *data, int *len);
 static int fdt_print(const char *pathp, char *prop, int depth);
 
 /*
@@ -63,7 +63,7 @@ void set_working_fdt_addr(void *addr)
 /*
  * Flattened Device Tree command, see the help for parameter definitions.
  */
-int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_fdt (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	if (argc < 2) {
 		cmd_usage(cmdtp);
@@ -515,7 +515,7 @@ static int fdt_valid(void)
  * data: A bytestream to be placed in the property
  * len: The length of the resulting bytestream
  */
-static int fdt_parse_prop(char **newval, int count, char *data, int *len)
+static int fdt_parse_prop(char * const *newval, int count, char *data, int *len)
 {
 	char *cp;		/* temporary char pointer */
 	char *newp;		/* temporary newval char pointer */