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authorWolfgang Denk <wd@denx.de>2010-06-28 22:00:46 +0200
committerWolfgang Denk <wd@denx.de>2010-07-04 23:55:42 +0200
commit54841ab50c20d6fa6c9cc3eb826989da3a22d934 (patch)
tree400f22f0a12ff0ae6c472bed6ac648befc1744a2 /include/command.h
parentb218ccb5435e64ac2318bb8b6c9594ef1cc724cd (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.h8
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 *[]);