mirror of
https://github.com/AsahiLinux/u-boot
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54841ab50c
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 <wd@denx.de>
Acked-by: Mike Frysinger <vapier@gentoo.org>
50 lines
1.5 KiB
C
50 lines
1.5 KiB
C
/*
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* Copyright 2000-2009
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* See file CREDITS for list of people who contributed to this
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* project.
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of
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* the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
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* MA 02111-1307 USA
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*/
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#include <common.h>
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#include <command.h>
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int do_help(cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
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{
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return _do_help(&__u_boot_cmd_start,
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&__u_boot_cmd_end - &__u_boot_cmd_start,
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cmdtp, flag, argc, argv);
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}
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U_BOOT_CMD(
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help, CONFIG_SYS_MAXARGS, 1, do_help,
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"print command description/usage",
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"\n"
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" - print brief description of all commands\n"
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"help command ...\n"
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" - print detailed usage of 'command'"
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);
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/* This does not use the U_BOOT_CMD macro as ? can't be used in symbol names */
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cmd_tbl_t __u_boot_cmd_question_mark Struct_Section = {
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"?", CONFIG_SYS_MAXARGS, 1, do_help,
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"alias for 'help'",
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#ifdef CONFIG_SYS_LONGHELP
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""
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#endif /* CONFIG_SYS_LONGHELP */
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};
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