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/include/command.h b/include/command.h
index 55caa6e..9144d69 100644
--- a/include/command.h
+++ b/include/command.h
@@ -48,14 +48,14 @@
int maxargs; /* maximum number of arguments */
int repeatable; /* autorepeat allowed? */
/* Implementation function */
- int (*cmd)(struct cmd_tbl_s *, int, int, char *[]);
+ int (*cmd)(struct cmd_tbl_s *, int, int, char * const []);
char *usage; /* Usage message (short) */
#ifdef CONFIG_SYS_LONGHELP
char *help; /* Help message (long) */
#endif
#ifdef CONFIG_AUTO_COMPLETE
/* do auto completion on the arguments */
- int (*complete)(int argc, char *argv[], char last_char, int maxv, char *cmdv[]);
+ int (*complete)(int argc, char * const argv[], char last_char, int maxv, char *cmdv[]);
#endif
};
@@ -67,7 +67,7 @@
/* common/command.c */
int _do_help (cmd_tbl_t *cmd_start, int cmd_items, cmd_tbl_t * cmdtp, int
- flag, int argc, char *argv[]);
+ flag, int argc, char * const argv[]);
cmd_tbl_t *find_cmd(const char *cmd);
cmd_tbl_t *find_cmd_tbl (const char *cmd, cmd_tbl_t *table, int table_len);
@@ -83,7 +83,7 @@
*
* All commands use a common argument format:
*
- * void function (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]);
+ * void function (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]);
*/
typedef void command_t (cmd_tbl_t *, int, int, char *[]);