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

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>

1 files changed, 8 insertions, 8 deletions

diff --git a/common/cmd_bedbug.c b/common/cmd_bedbug.c
index 8be1c25fd7..d01ee19ee5 100644
--- a/common/cmd_bedbug.c
+++ b/common/cmd_bedbug.c
@@ -73,7 +73,7 @@ void bedbug_init (void)
  * Entry point from the interpreter to the disassembler.  Repeated calls
  * will resume from the last disassembled address.
  * ====================================================================== */
-int do_bedbug_dis (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_dis (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	ulong addr;		/* Address to start disassembly from    */
 	ulong len;		/* # of instructions to disassemble     */
@@ -115,7 +115,7 @@ U_BOOT_CMD (ds, 3, 1, do_bedbug_dis,
  * instructions in consecutive memory locations until a '.' (period) is
  * entered on a line by itself.
  * ====================================================================== */
-int do_bedbug_asm (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_asm (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	long mem_addr;		/* Address to assemble into     */
 	unsigned long instr;	/* Machine code for text        */
@@ -167,7 +167,7 @@ U_BOOT_CMD (as, 2, 0, do_bedbug_asm,
  * CPU-specific break point set routine.
  * ====================================================================== */
 
-int do_bedbug_break (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_break (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	/* -------------------------------------------------- */
 	if (bug_ctx.do_break)
@@ -263,7 +263,7 @@ void bedbug_main_loop (unsigned long addr, struct pt_regs *regs)
  * stopped flag in the context so that the breakpoint routine will
  * return.
  * ====================================================================== */
-int do_bedbug_continue (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_continue (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	/* -------------------------------------------------- */
 
@@ -286,7 +286,7 @@ U_BOOT_CMD (continue, 1, 0, do_bedbug_continue,
  * the address passes control to the CPU-specific set breakpoint routine
  * for the current breakpoint number.
  * ====================================================================== */
-int do_bedbug_step (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_step (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned long addr;	/* Address to stop at */
 
@@ -317,7 +317,7 @@ U_BOOT_CMD (step, 1, 1, do_bedbug_step,
  * the address passes control to the CPU-specific set breakpoint routine
  * for the current breakpoint number.
  * ====================================================================== */
-int do_bedbug_next (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_next (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned long addr;	/* Address to stop at */
 
@@ -346,7 +346,7 @@ U_BOOT_CMD (next, 1, 1, do_bedbug_next,
  * Interpreter command to print the current stack.  This assumes an EABI
  * architecture, so it starts with GPR R1 and works back up the stack.
  * ====================================================================== */
-int do_bedbug_stack (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_stack (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	unsigned long sp;	/* Stack pointer                */
 	unsigned long func;	/* LR from stack                */
@@ -391,7 +391,7 @@ U_BOOT_CMD (where, 1, 1, do_bedbug_stack,
  * Interpreter command to dump the registers.  Calls the CPU-specific
  * show registers routine.
  * ====================================================================== */
-int do_bedbug_rdump (cmd_tbl_t * cmdtp, int flag, int argc, char *argv[])
+int do_bedbug_rdump (cmd_tbl_t * cmdtp, int flag, int argc, char * const argv[])
 {
 	/* -------------------------------------------------- */