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/cmd_load.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'common/cmd_load.c') diff --git a/common/cmd_load.c b/common/cmd_load.c index d6bbb786d..52ed1fa70 100644 --- a/common/cmd_load.c +++ b/common/cmd_load.c @@ -51,7 +51,7 @@ static int do_echo = 1; /* -------------------------------------------------------------------- */ #if defined(CONFIG_CMD_LOADS) -int do_load_serial (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_load_serial (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { long offset = 0; ulong addr; @@ -255,7 +255,7 @@ read_record (char *buf, ulong len) #if defined(CONFIG_CMD_SAVES) -int do_save_serial (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_save_serial (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { ulong offset = 0; ulong size = 0; @@ -433,7 +433,7 @@ int his_pad_count; /* number of pad chars he needs */ char his_pad_char; /* pad chars he needs */ char his_quote; /* quote chars he'll use */ -int do_load_serial_bin (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_load_serial_bin (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { ulong offset = 0; ulong addr; @@ -1091,7 +1091,7 @@ U_BOOT_CMD( /* -------------------------------------------------------------------- */ #if defined(CONFIG_CMD_HWFLOW) -int do_hwflow (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_hwflow (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { extern int hwflow_onoff(int); -- cgit v1.2.3-70-g09d2