mirror of
https://github.com/brain-hackers/u-boot-brain
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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>
82 lines
2.1 KiB
C
82 lines
2.1 KiB
C
/*
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* (C) Copyright 2006
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* Detlev Zundel, DENX Software Engineering, dzu@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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* This is a very simple standalone application demonstrating
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* catching IRQs on the MPC52xx architecture.
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*
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* The interrupt to be intercepted can be specified as an argument
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* to the application. Specifying nothing will intercept IRQ1 on the
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* MPC5200 platform. On the CR825 carrier board from MicroSys this
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* maps to the ABORT switch :)
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*
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* Note that the specified vector is only a logical number specified
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* by the respective header file.
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*/
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#include <common.h>
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#include <exports.h>
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#include <config.h>
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#if defined(CONFIG_MPC5xxx)
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#define DFL_IRQ MPC5XXX_IRQ1
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#else
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#define DFL_IRQ 0
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#endif
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static void irq_handler (void *arg);
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int interrupt (int argc, char * const argv[])
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{
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int c, irq = -1;
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app_startup (argv);
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if (argc > 1)
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irq = simple_strtoul (argv[1], NULL, 0);
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if ((irq < 0) || (irq > NR_IRQS))
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irq = DFL_IRQ;
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printf ("Installing handler for irq vector %d and doing busy wait\n",
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irq);
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printf ("Press 'q' to quit\n");
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/* Install interrupt handler */
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install_hdlr (irq, irq_handler, NULL);
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while ((c = getc ()) != 'q') {
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printf ("Ok, ok, I am still alive!\n");
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}
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free_hdlr (irq);
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printf ("\nInterrupt handler has been uninstalled\n");
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return (0);
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}
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/*
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* Handler for interrupt
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*/
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static void irq_handler (void *arg)
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{
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/* just for demonstration */
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printf ("+");
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}
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