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 --- board/tqc/tqm5200/cmd_tb5200.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'board/tqc/tqm5200/cmd_tb5200.c') diff --git a/board/tqc/tqm5200/cmd_tb5200.c b/board/tqc/tqm5200/cmd_tb5200.c index 578e716e7a..79c1b980a2 100644 --- a/board/tqc/tqm5200/cmd_tb5200.c +++ b/board/tqc/tqm5200/cmd_tb5200.c @@ -42,7 +42,7 @@ static void led_init(void) gpt->gpt4.emsr |= 0x00000024; } -int cmd_led(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int cmd_led(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { struct mpc5xxx_gpt_0_7 *gpt = (struct mpc5xxx_gpt_0_7 *)MPC5XXX_GPT; @@ -72,7 +72,7 @@ static void sm501_backlight (unsigned int state) ~((1 << 26) | (1 << 27)); } -int cmd_backlight(cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int cmd_backlight(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { if (strcmp (argv[1], "on") == 0) { debug ("switch backlight on\n"); -- cgit v1.2.3