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/main.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) (limited to 'common/main.c') diff --git a/common/main.c b/common/main.c index 3760ba3d6b..20090ee6aa 100644 --- a/common/main.c +++ b/common/main.c @@ -51,10 +51,10 @@ void inline __show_boot_progress (int val) {} void show_boot_progress (int val) __attribute__((weak, alias("__show_boot_progress"))); #if defined(CONFIG_BOOT_RETRY_TIME) && defined(CONFIG_RESET_TO_RETRY) -extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]); /* for do_reset() prototype */ +extern int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]); /* for do_reset() prototype */ #endif -extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]); +extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]); #if defined(CONFIG_UPDATE_TFTP) void update_tftp (void); @@ -1414,7 +1414,7 @@ int run_command (const char *cmd, int flag) /****************************************************************************/ #if defined(CONFIG_CMD_RUN) -int do_run (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[]) +int do_run (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[]) { int i; -- cgit v1.2.3