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 --- arch/powerpc/cpu/ppc4xx/bedbug_405.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'arch/powerpc/cpu/ppc4xx/bedbug_405.c') diff --git a/arch/powerpc/cpu/ppc4xx/bedbug_405.c b/arch/powerpc/cpu/ppc4xx/bedbug_405.c index ef11cb65e41..e1500cc0422 100644 --- a/arch/powerpc/cpu/ppc4xx/bedbug_405.c +++ b/arch/powerpc/cpu/ppc4xx/bedbug_405.c @@ -17,7 +17,7 @@ extern CPU_DEBUG_CTX bug_ctx; void bedbug405_init __P ((void)); -void bedbug405_do_break __P ((cmd_tbl_t *, int, int, char *[])); +void bedbug405_do_break __P ((cmd_tbl_t *, int, int, char * const [])); void bedbug405_break_isr __P ((struct pt_regs *)); int bedbug405_find_empty __P ((void)); int bedbug405_set __P ((int, unsigned long)); @@ -63,7 +63,7 @@ void bedbug405_init (void) * set routine which will assign a breakpoint number. * ====================================================================== */ -void bedbug405_do_break (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +void bedbug405_do_break (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { long addr = 0; /* Address to break at */ int which_bp; /* Breakpoint number */ -- cgit v1.2.3