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_boot.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/cmd_boot.c') diff --git a/common/cmd_boot.c b/common/cmd_boot.c index bfc1db2..9ccc8c7 100644 --- a/common/cmd_boot.c +++ b/common/cmd_boot.c @@ -30,12 +30,12 @@ /* Allow ports to override the default behavior */ __attribute__((weak)) -unsigned long do_go_exec (ulong (*entry)(int, char *[]), int argc, char *argv[]) +unsigned long do_go_exec (ulong (*entry)(int, char * const []), int argc, char * const argv[]) { return entry (argc, argv); } -int do_go (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_go (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { ulong addr, rc; int rcode = 0; @@ -69,7 +69,7 @@ U_BOOT_CMD( " passing 'arg' as arguments" ); -extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]); +extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]); U_BOOT_CMD( reset, 1, 0, do_reset, -- cgit v1.1