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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>
64 lines
1.2 KiB
C
64 lines
1.2 KiB
C
/*
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* U-boot - boot.c - misc boot helper functions
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*
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* Copyright (c) 2005-2008 Analog Devices Inc.
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*
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* (C) Copyright 2000-2004
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* Wolfgang Denk, DENX Software Engineering, wd@denx.de.
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*
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* Licensed under the GPL-2 or later.
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*/
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#include <common.h>
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#include <command.h>
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#include <image.h>
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#include <asm/blackfin.h>
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#ifdef SHARED_RESOURCES
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extern void swap_to(int device_id);
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#endif
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static char *make_command_line(void)
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{
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char *dest = (char *)CONFIG_LINUX_CMDLINE_ADDR;
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char *bootargs = getenv("bootargs");
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if (bootargs == NULL)
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return NULL;
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strncpy(dest, bootargs, CONFIG_LINUX_CMDLINE_SIZE);
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dest[CONFIG_LINUX_CMDLINE_SIZE - 1] = 0;
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return dest;
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}
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extern ulong bfin_poweron_retx;
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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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int (*appl) (char *cmdline);
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char *cmdline;
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if ((flag != 0) && (flag != BOOTM_STATE_OS_GO))
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return 1;
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#ifdef SHARED_RESOURCES
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swap_to(FLASH);
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#endif
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appl = (int (*)(char *))images->ep;
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printf("Starting Kernel at = %p\n", appl);
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cmdline = make_command_line();
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icache_disable();
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dcache_disable();
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asm __volatile__(
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"RETX = %[retx];"
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"CALL (%0);"
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:
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: "p"(appl), "q0"(cmdline), [retx] "d"(bfin_poweron_retx)
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);
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/* does not return */
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return 1;
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}
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