From 54841ab50c20d6fa6c9cc3eb826989da3a22d934 Mon Sep 17 00:00:00 2001 From: Wolfgang Denk Date: Mon, 28 Jun 2010 22:00:46 +0200 Subject: 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 Acked-by: Mike Frysinger --- common/command.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'common/command.c') 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; -- cgit v1.1