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/esd/ar405/ar405.c b/board/esd/ar405/ar405.c
index a632cb4..21b2432 100644
--- a/board/esd/ar405/ar405.c
+++ b/board/esd/ar405/ar405.c
@@ -30,7 +30,7 @@
DECLARE_GLOBAL_DATA_PTR;
/*cmd_boot.c*/
-extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
extern void lxt971_no_sleep(void);
/* ------------------------------------------------------------------------- */
@@ -196,7 +196,7 @@
/*
* Some test routines
*/
-int do_digtest(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_digtest(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
int i;
int k;
@@ -257,7 +257,7 @@
short dummy;
};
-int do_anatest(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_anatest(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
short val;
int i;
@@ -353,7 +353,7 @@
}
-int do_inctest(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
+int do_inctest(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
ulong *incin;
int i;