From 54841ab50c20d6fa6c9cc3eb826989da3a22d934 Mon Sep 17 00:00:00 2001 From: Wolfgang Denk Date: Mon, 28 Jun 2010 22:00:46 +0200 Subject: 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 Acked-by: Mike Frysinger --- arch/powerpc/cpu/mpc8xx/bedbug_860.c | 4 ++-- arch/powerpc/cpu/mpc8xx/cpu.c | 4 ++-- 2 files changed, 4 insertions(+), 4 deletions(-) (limited to 'arch/powerpc/cpu/mpc8xx') diff --git a/arch/powerpc/cpu/mpc8xx/bedbug_860.c b/arch/powerpc/cpu/mpc8xx/bedbug_860.c index 0308bbb..9deda6c 100644 --- a/arch/powerpc/cpu/mpc8xx/bedbug_860.c +++ b/arch/powerpc/cpu/mpc8xx/bedbug_860.c @@ -17,7 +17,7 @@ extern CPU_DEBUG_CTX bug_ctx; void bedbug860_init __P((void)); -void bedbug860_do_break __P((cmd_tbl_t*,int,int,char*[])); +void bedbug860_do_break __P((cmd_tbl_t*,int,int,char*const[])); void bedbug860_break_isr __P((struct pt_regs*)); int bedbug860_find_empty __P((void)); int bedbug860_set __P((int,unsigned long)); @@ -63,7 +63,7 @@ void bedbug860_init( void ) * ====================================================================== */ void bedbug860_do_break (cmd_tbl_t *cmdtp, int flag, int argc, - char *argv[]) + char * const argv[]) { long addr = 0; /* Address to break at */ int which_bp; /* Breakpoint number */ diff --git a/arch/powerpc/cpu/mpc8xx/cpu.c b/arch/powerpc/cpu/mpc8xx/cpu.c index 2eb848b..142cfa5 100644 --- a/arch/powerpc/cpu/mpc8xx/cpu.c +++ b/arch/powerpc/cpu/mpc8xx/cpu.c @@ -478,7 +478,7 @@ void upmconfig (uint upm, uint * table, uint size) #ifndef CONFIG_LWMON -int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { ulong msr, addr; @@ -521,7 +521,7 @@ int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) * and thus too short to reset the external hardware. So we use the * watchdog to reset the board. */ -int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char *argv[]) +int do_reset (cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[]) { /* prevent triggering the watchdog */ disable_interrupts (); -- cgit v1.1