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_portio.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'common/cmd_portio.c') diff --git a/common/cmd_portio.c b/common/cmd_portio.c index f8befee296..92d61d206f 100644 --- a/common/cmd_portio.c +++ b/common/cmd_portio.c @@ -37,7 +37,7 @@ static uint in_last_addr, in_last_size; static uint out_last_addr, out_last_size, out_last_value; -int do_portio_out (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_portio_out (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { uint addr = out_last_addr; uint size = out_last_size; @@ -97,7 +97,7 @@ U_BOOT_CMD( "[.b, .w, .l] port value\n - output to IO port" ); -int do_portio_in (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_portio_in (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { uint addr = in_last_addr; uint size = in_last_size; -- cgit v1.2.1