diff options
author | Wolfgang Denk <wd@denx.de> | 2010-06-28 22:00:46 +0200 |
---|---|---|
committer | Wolfgang Denk <wd@denx.de> | 2010-07-04 23:55:42 +0200 |
commit | 54841ab50c20d6fa6c9cc3eb826989da3a22d934 (patch) | |
tree | 400f22f0a12ff0ae6c472bed6ac648befc1744a2 /include/command.h | |
parent | b218ccb5435e64ac2318bb8b6c9594ef1cc724cd (diff) |
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>
Diffstat (limited to 'include/command.h')
-rw-r--r-- | include/command.h | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/include/command.h b/include/command.h index 55caa6eaf8..9144d69206 100644 --- a/include/command.h +++ b/include/command.h @@ -48,14 +48,14 @@ struct cmd_tbl_s { 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 @@ extern cmd_tbl_t __u_boot_cmd_end; /* 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 @@ extern int cmd_auto_complete(const char *const prompt, char *buf, int *np, int * * * 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 *[]); |