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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>
53 lines
1.8 KiB
C
53 lines
1.8 KiB
C
/*
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* (C) Copyright 2003, Psyent Corporation <www.psyent.com>
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* Scott McNutt <smcnutt@psyent.com>
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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 <asm/byteorder.h>
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#include <asm/cache.h>
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#define NIOS_MAGIC 0x534f494e /* enable command line and initrd passing */
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int do_bootm_linux(int flag, int argc, char * const argv[], bootm_headers_t *images)
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{
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void (*kernel)(int, int, int, char *) = (void *)images->ep;
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char *commandline = getenv("bootargs");
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ulong initrd_start = images->rd_start;
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ulong initrd_end = images->rd_end;
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if ((flag != 0) && (flag != BOOTM_STATE_OS_GO))
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return 1;
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/* flushes data and instruction caches before calling the kernel */
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disable_interrupts();
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flush_dcache((ulong)kernel, CONFIG_SYS_DCACHE_SIZE);
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flush_icache((ulong)kernel, CONFIG_SYS_ICACHE_SIZE);
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debug("bootargs=%s @ 0x%lx\n", commandline, (ulong)&commandline);
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debug("initrd=0x%lx-0x%lx\n", (ulong)initrd_start, (ulong)initrd_end);
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kernel(NIOS_MAGIC, initrd_start, initrd_end, commandline);
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/* does not return */
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return 1;
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}
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