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/bc3450/cmd_bc3450.c | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-) (limited to 'board/bc3450') diff --git a/board/bc3450/cmd_bc3450.c b/board/bc3450/cmd_bc3450.c index 271ffb1..a9e4902 100644 --- a/board/bc3450/cmd_bc3450.c +++ b/board/bc3450/cmd_bc3450.c @@ -173,7 +173,7 @@ int sm501_gpio_init (void) * read and prints the dip switch * and/or external config inputs (4bits) 0...0x0F */ -int cmd_dip (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int cmd_dip (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { vu_long rc = 0; @@ -205,7 +205,7 @@ U_BOOT_CMD (dip, 1, 1, cmd_dip, * buz - turns Buzzer on/off */ #ifdef CONFIG_BC3450_BUZZER -static int cmd_buz (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +static int cmd_buz (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { if (argc != 2) { printf ("Usage:\nspecify one argument: \"on\" or \"off\"\n"); @@ -236,7 +236,7 @@ U_BOOT_CMD (buz, 2, 1, cmd_buz, /* * fp - front panel commands */ -static int cmd_fp (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +static int cmd_fp (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { sm501_gpio_init (); @@ -491,7 +491,7 @@ static void ds1620_write_state (struct therm *therm) ds1620_out (THERM_START_CONVERT, 0, 0); } -static int cmd_temp (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +static int cmd_temp (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { int i; struct therm therm; @@ -682,7 +682,7 @@ int can_init (void) * return 1 on CAN failure * return 0 if no failure */ -int do_can (char *argv[]) +int do_can (char * const argv[]) { int i; struct mpc5xxx_mscan *can1 = @@ -777,7 +777,7 @@ int do_can (char *argv[]) /* * test - BC3450 HW test routines */ -int cmd_test (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int cmd_test (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { #ifdef CONFIG_BC3450_CAN int rcode; -- cgit v1.1