commit 54841ab50c20d6fa6c9cc3eb826989da3a22d934
author Wolfgang Denk <wd@denx.de> Mon Jun 28 22:00:46 2010 +0200
committer Wolfgang Denk <wd@denx.de> Sun Jul 04 23:55:42 2010 +0200
tree 400f22f0a12ff0ae6c472bed6ac648befc1744a2
parent b218ccb5435e64ac2318bb8b6c9594ef1cc724cd

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>

arch/nios2/cpu/epcs.c

diff --git a/arch/nios2/cpu/epcs.c b/arch/nios2/cpu/epcs.c
index ab7d746..2369431 100644
--- a/arch/nios2/cpu/epcs.c
+++ b/arch/nios2/cpu/epcs.c
@@ -472,7 +472,7 @@
  * Commands
  ***********************************************************************/
 static
-void do_epcs_info (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_info (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	int i;
 	unsigned char stat;
@@ -519,7 +519,7 @@
 }
 
 static
-void do_epcs_erase (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_erase (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	unsigned start,end;
 
@@ -549,7 +549,7 @@
 }
 
 static
-void do_epcs_protect (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_protect (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	unsigned char stat;
 
@@ -585,7 +585,7 @@
 }
 
 static
-void do_epcs_read (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_read (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	ulong addr,off,cnt;
 	ulong sz;
@@ -617,7 +617,7 @@
 }
 
 static
-void do_epcs_write (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_write (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	ulong addr,off,cnt;
 	ulong sz;
@@ -656,7 +656,7 @@
 }
 
 static
-void do_epcs_verify (struct epcs_devinfo_t *dev, int argc, char *argv[])
+void do_epcs_verify (struct epcs_devinfo_t *dev, int argc, char * const argv[])
 {
 	ulong addr,off,cnt;
 	ulong sz;
@@ -690,7 +690,7 @@
 }
 
 /*-----------------------------------------------------------------------*/
-int do_epcs (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_epcs (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	int len;
 	struct epcs_devinfo_t *dev = epcs_dev_find ();