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Make sure that argv[] argument pointers are not modified.

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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>
This commit is contained in:
Wolfgang Denk 2010-06-28 22:00:46 +02:00
parent b218ccb543
commit 54841ab50c
295 changed files with 671 additions and 670 deletions
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7
common/cmd_elf.c
View file

@ -29,7 +29,8 @@ unsigned long load_elf_image (unsigned long addr);
/* Allow ports to override the default behavior */
__attribute__((weak))
unsigned long do_bootelf_exec (ulong (*entry)(int, char *[]), int argc, char *argv[])
unsigned long do_bootelf_exec (ulong (*entry)(int, char * const[]),
int argc, char * const argv[])
{
unsigned long ret;
@ -56,7 +57,7 @@ unsigned long do_bootelf_exec (ulong (*entry)(int, char *[]), int argc, char *ar
/* ======================================================================
* Interpreter command to boot an arbitrary ELF image from memory.
* ====================================================================== */
int do_bootelf (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
int do_bootelf (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
unsigned long addr; /* Address of the ELF image */
unsigned long rc; /* Return value from user code */
@ -93,7 +94,7 @@ int do_bootelf (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
* be either an ELF image or a raw binary. Will attempt to setup the
* bootline and other parameters correctly.
* ====================================================================== */
int do_bootvx (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[])
int do_bootvx (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
{
unsigned long addr; /* Address of image */
unsigned long bootaddr; /* Address to put the bootline */