mirror of
https://github.com/AsahiLinux/u-boot
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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>
12 lines
419 B
C
12 lines
419 B
C
/* A little trick taken from the kernel asm-offsets.h where we convert
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* the C structures automatically into a bunch of defines for use in
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* the assembly files.
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*/
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#include <linux/stddef.h>
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#include <asm/mach-common/bits/bootrom.h>
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#define _DEFINE(sym, val) asm volatile("\n->" #sym " %0 " #val : : "i" (val))
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#define DEFINE(s, m) _DEFINE(offset_##s##_##m, offsetof(s, m))
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int main(int argc, char * const argv[])
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