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/hush.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) (limited to 'common/hush.c') diff --git a/common/hush.c b/common/hush.c index 9eea90f42..8a74d225e 100644 --- a/common/hush.c +++ b/common/hush.c @@ -94,7 +94,7 @@ #include #include /* find_cmd */ /*cmd_boot.c*/ -extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]); /* do_bootd */ +extern int do_bootd (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]); /* do_bootd */ #endif #ifndef __U_BOOT__ #include /* isalpha, isdigit */ @@ -1024,7 +1024,7 @@ static void get_user_input(struct in_str *i) #ifdef CONFIG_BOOT_RETRY_TIME # ifdef CONFIG_RESET_TO_RETRY - 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[]); # else # error "This currently only works with CONFIG_RESET_TO_RETRY enabled" # endif @@ -1681,7 +1681,7 @@ static int run_pipe_real(struct pipe *pi) } else { int rcode; #if defined(CONFIG_CMD_BOOTD) - 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[]); /* avoid "bootd" recursion */ if (cmdtp->cmd == do_bootd) { @@ -3351,7 +3351,7 @@ static void setup_job_control(void) tcsetpgrp(shell_terminal, shell_pgrp); } -int hush_main(int argc, char **argv) +int hush_main(int argc, char * const *argv) { int opt; FILE *input; @@ -3588,7 +3588,7 @@ static char * make_string(char ** inp) } #ifdef __U_BOOT__ -int do_showvar (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_showvar (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { int i, k; int rcode = 0; -- cgit v1.2.3-70-g09d2