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https://github.com/brain-hackers/u-boot-brain
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![Wolfgang Denk](/assets/img/avatar_default.png)
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>
86 lines
2.3 KiB
C
86 lines
2.3 KiB
C
/*
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* (C) Copyright 2007
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* Stefano Babic, DENX Software Engineering, sbabic@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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#include <dm9000.h>
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static int do_read_dm9000_eeprom ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) {
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unsigned int i;
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u8 data[2];
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for (i=0; i < 0x40; i++) {
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if (!(i % 0x10))
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printf("\n%08x:", i);
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dm9000_read_srom_word(i, data);
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printf(" %02x%02x", data[1], data[0]);
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}
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printf ("\n");
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return (0);
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}
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static int do_write_dm9000_eeprom ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) {
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int offset,value;
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if (argc < 4) {
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cmd_usage(cmdtp);
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return 1;
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}
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offset=simple_strtoul(argv[2],NULL,16);
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value=simple_strtoul(argv[3],NULL,16);
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if (offset > 0x40) {
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printf("Wrong offset : 0x%x\n",offset);
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cmd_usage(cmdtp);
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return 1;
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}
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dm9000_write_srom_word(offset, value);
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return (0);
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}
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int do_dm9000_eeprom ( cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) {
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if (argc < 2) {
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cmd_usage(cmdtp);
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return 1;
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}
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if (strcmp (argv[1],"read") == 0) {
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return (do_read_dm9000_eeprom(cmdtp,flag,argc,argv));
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} else if (strcmp (argv[1],"write") == 0) {
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return (do_write_dm9000_eeprom(cmdtp,flag,argc,argv));
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} else {
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cmd_usage(cmdtp);
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return 1;
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}
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}
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U_BOOT_CMD(
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dm9000ee,4,1,do_dm9000_eeprom,
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"Read/Write eeprom connected to Ethernet Controller",
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"\ndm9000ee write <word offset> <value> \n"
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"\tdm9000ee read \n"
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"\tword:\t\t00-02 : MAC Address\n"
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"\t\t\t03-07 : DM9000 Configuration\n"
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"\t\t\t08-63 : User data"
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);
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