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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 /common/command.c
parentb218ccb5435e64ac2318bb8b6c9594ef1cc724cd (diff)
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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 'common/command.c')
-rw-r--r--common/command.c12
1 files changed, 6 insertions, 6 deletions
diff --git a/common/command.c b/common/command.c
index 67ad692..a1fc592 100644
--- a/common/command.c
+++ b/common/command.c
@@ -34,7 +34,7 @@
*/
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[])
{
int i;
int rcode = 0;
@@ -158,7 +158,7 @@ int cmd_usage(cmd_tbl_t *cmdtp)
#ifdef CONFIG_AUTO_COMPLETE
-int var_complete(int argc, char *argv[], char last_char, int maxv, char *cmdv[])
+int var_complete(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
{
static char tmp_buf[512];
int space;
@@ -175,7 +175,7 @@ int var_complete(int argc, char *argv[], char last_char, int maxv, char *cmdv[])
}
static void install_auto_complete_handler(const char *cmd,
- 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[]))
{
cmd_tbl_t *cmdtp;
@@ -200,7 +200,7 @@ void install_auto_complete(void)
/*************************************************************************************/
-static int complete_cmdv(int argc, char *argv[], char last_char, int maxv, char *cmdv[])
+static int complete_cmdv(int argc, char * const argv[], char last_char, int maxv, char *cmdv[])
{
cmd_tbl_t *cmdtp;
const char *p;
@@ -301,7 +301,7 @@ static int make_argv(char *s, int argvsz, char *argv[])
return argc;
}
-static void print_argv(const char *banner, const char *leader, const char *sep, int linemax, char *argv[])
+static void print_argv(const char *banner, const char *leader, const char *sep, int linemax, char * const argv[])
{
int ll = leader != NULL ? strlen(leader) : 0;
int sl = sep != NULL ? strlen(sep) : 0;
@@ -328,7 +328,7 @@ static void print_argv(const char *banner, const char *leader, const char *sep,
printf("\n");
}
-static int find_common_prefix(char *argv[])
+static int find_common_prefix(char * const argv[])
{
int i, len;
char *anchor, *s, *t;