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>
diff --git a/board/cm5200/fwupdate.c b/board/cm5200/fwupdate.c
index 5a27191..c1a4a19 100644
--- a/board/cm5200/fwupdate.c
+++ b/board/cm5200/fwupdate.c
@@ -35,9 +35,9 @@
#include "fwupdate.h"
-extern int do_bootm(cmd_tbl_t *, int, int, char *[]);
+extern int do_bootm(cmd_tbl_t *, int, int, char * const []);
extern long do_fat_read(const char *, void *, unsigned long, int);
-extern int do_fat_fsload(cmd_tbl_t *, int, int, char *[]);
+extern int do_fat_fsload(cmd_tbl_t *, int, int, char * const []);
static int load_rescue_image(ulong);
@@ -47,7 +47,7 @@
char *rsargs;
char *tmp = NULL;
char ka[16];
- char *argv[3] = { "bootm", ka, NULL };
+ char * const argv[3] = { "bootm", ka, NULL };
/* Check if rescue system is disabled... */
if (getenv("norescue")) {
@@ -99,7 +99,7 @@
char *tmp;
char dev[7];
char addr_str[16];
- char *argv[6] = { "fatload", "usb", dev, addr_str, nxri, NULL };
+ char * const argv[6] = { "fatload", "usb", dev, addr_str, nxri, NULL };
block_dev_desc_t *stor_dev = NULL;
cmd_tbl_t *bcmd;