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/lwmon5/kbd.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'board/lwmon5/kbd.c') diff --git a/board/lwmon5/kbd.c b/board/lwmon5/kbd.c index be1a1dfeb5..0e26b890b2 100644 --- a/board/lwmon5/kbd.c +++ b/board/lwmon5/kbd.c @@ -380,7 +380,7 @@ static uchar *key_match (uchar *kbd_data) /*********************************************************************** F* Function: int do_kbd (cmd_tbl_t *cmdtp, int flag, -F* int argc, char *argv[]) P*A*Z* +F* int argc, char * const argv[]) P*A*Z* * P* Parameters: cmd_tbl_t *cmdtp P* - Pointer to our command table entry @@ -389,7 +389,7 @@ P* - If the CMD_FLAG_REPEAT bit is set, then this call is P* a repetition P* int argc P* - Argument count -P* char *argv[] +P* char * const argv[] P* - Array of the actual arguments P* P* Returnvalue: int @@ -404,7 +404,7 @@ D* Design: wd@denx.de C* Coding: wd@denx.de V* Verification: dzu@denx.de ***********************************************************************/ -int do_kbd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_kbd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { uchar kbd_data[KEYBD_DATALEN]; char keybd_env[2 * KEYBD_DATALEN + 1]; -- cgit v1.2.1