mirror of
https://github.com/brain-hackers/u-boot-brain
synced 2024-06-09 23:36:03 +09:00
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>
97 lines
2.5 KiB
C
97 lines
2.5 KiB
C
/*
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* Copyright 2008 Freescale Semiconductor, Inc.
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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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/*
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* This file provides a shell like 'expr' function to return.
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*/
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#include <common.h>
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#include <config.h>
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#include <command.h>
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static ulong get_arg(char *s, int w)
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{
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ulong *p;
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/*
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* if the parameter starts with a '*' then assume
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* it is a pointer to the value we want
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*/
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if (s[0] == '*') {
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p = (ulong *)simple_strtoul(&s[1], NULL, 16);
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switch (w) {
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case 1: return((ulong)(*(uchar *)p));
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case 2: return((ulong)(*(ushort *)p));
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case 4:
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default: return(*p);
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}
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} else {
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return simple_strtoul(s, NULL, 16);
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}
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}
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int do_setexpr(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
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{
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ulong a, b;
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char buf[16];
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int w;
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/* Validate arguments */
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if ((argc != 5) || (strlen(argv[3]) != 1)) {
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cmd_usage(cmdtp);
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return 1;
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}
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w = cmd_get_data_size(argv[0], 4);
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a = get_arg(argv[2], w);
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b = get_arg(argv[4], w);
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switch (argv[3][0]) {
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case '|': sprintf(buf, "%lx", (a | b)); break;
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case '&': sprintf(buf, "%lx", (a & b)); break;
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case '+': sprintf(buf, "%lx", (a + b)); break;
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case '^': sprintf(buf, "%lx", (a ^ b)); break;
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case '-': sprintf(buf, "%lx", (a - b)); break;
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case '*': sprintf(buf, "%lx", (a * b)); break;
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case '/': sprintf(buf, "%lx", (a / b)); break;
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case '%': sprintf(buf, "%lx", (a % b)); break;
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default:
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printf("invalid op\n");
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return 1;
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}
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setenv(argv[1], buf);
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return 0;
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}
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U_BOOT_CMD(
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setexpr, 5, 0, do_setexpr,
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"set environment variable as the result of eval expression",
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"[.b, .w, .l] name value1 <op> value2\n"
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" - set environment variable 'name' to the result of the evaluated\n"
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" express specified by <op>. <op> can be &, |, ^, +, -, *, /, %\n"
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" size argument is only meaningful if value1 and/or value2 are memory addresses"
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);
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