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>

common/cmd_immap.c

diff --git a/common/cmd_immap.c b/common/cmd_immap.c
index 37e6058..1f59c1e 100644
--- a/common/cmd_immap.c
+++ b/common/cmd_immap.c
@@ -43,14 +43,14 @@
 DECLARE_GLOBAL_DATA_PTR;
 
 static void
-unimplemented ( cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+unimplemented ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	printf ("Sorry, but the '%s' command has not been implemented\n",
 		cmdtp->name);
 }
 
 int
-do_siuinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_siuinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -81,7 +81,7 @@
 }
 
 int
-do_memcinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_memcinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -133,7 +133,7 @@
 }
 
 int
-do_sitinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_sitinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
@@ -141,7 +141,7 @@
 
 #ifdef CONFIG_8260
 int
-do_icinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_icinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
@@ -149,7 +149,7 @@
 #endif
 
 int
-do_carinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_carinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -233,7 +233,7 @@
 #endif
 
 int
-do_iopinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_iopinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -316,7 +316,7 @@
  * use *uint and set the address based on cmd + port
  */
 int
-do_iopset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_iopset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	uint rcode = 0;
 	iopin_t iopin;
@@ -431,14 +431,14 @@
 }
 
 int
-do_dmainfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_dmainfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_fccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_fccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
@@ -498,7 +498,7 @@
 }
 
 int
-do_brginfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_brginfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -522,7 +522,7 @@
 }
 
 int
-do_i2cinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_i2cinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	volatile immap_t *immap = (immap_t *) CONFIG_SYS_IMMR;
 
@@ -569,42 +569,42 @@
 }
 
 int
-do_sccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_sccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_smcinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_smcinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_spiinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_spiinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_muxinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_muxinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_siinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_siinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;
 }
 
 int
-do_mccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+do_mccinfo (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 {
 	unimplemented (cmdtp, flag, argc, argv);
 	return 0;