[PATCH] autoboot: fix illegal memory access when stop key and delay key are empty

[Andy.Wu at sony.com <Andy.Wu@sony.com>]

> > You could avoid the subtraction instead of changing the type:
> >
> > -for (i = 0; i < presskey_max - 1; i++)
> > +for (i = 0; i + 1 < presskey_max; i++)
> This style seems not typically way for for loop, how do you think?
I found one similar for loop style in u-boot source code, it seems aim to fix the similar issue.

$ grep -rn "i = 0; i + 1 < " . | grep for
drivers/i2c/meson_i2c.c:132:    for (i = 0; i + 1 < i2c->count; i++)

This for loop style just 1 place compared with common style 3926 in u-boot.

$ grep -rn "i = 0; i + 1 < " . | grep for | wc -l
1
$ grep -rn "i = 0; i < " . | grep for | wc -l
3926

Best Regards
Andy Wu

> -----Original Message-----
> From: U-Boot <u-boot-bounces@lists.denx.de> On Behalf Of
> Andy.Wu at sony.com
> Sent: Monday, January 18, 2021 1:22 PM
> To: xypron.glpk at gmx.de; Mo, Yuezhang <Yuezhang.Mo@sony.com>;
> u-boot at lists.denx.de
> Cc: sjg at chromium.org; hs at denx.de
> Subject: RE: [PATCH] autoboot: fix illegal memory access when stop key and
> delay key are empty
> 
> > Both indices cannot be negative. So it is understandable that u_int was chosen.
> Yes, u_int is understandable that the length is never be negative, but define the
> length parameter as "int" also usable.
> Some example in current u-boot source code:
> 
> $ grep -rn length common/ | grep "int "
> common/usb_storage.c:363:static int us_one_transfer(struct us_data *us, int
> pipe, char *buf, int length) common/lcd.c:52:int lcd_line_length;
> common/lcd.c:66:        int line_length;
> common/lcd.c:143:__weak int lcd_get_size(int *line_length)
> common/lcd.c:283:       int line_length;
> common/usb.c:275:                       void *data, int len, int
> *actual_length, int timeout)
> common/usb.c:600:                            unsigned char *buffer, int
> length)
> common/usb.c:751:static void usb_try_string_workarounds(unsigned char *buf,
> int *length)
> common/usb.c:753:       int newlength, oldlength = *length;
> common/kgdb.c:319:      int length;
> common/cli_hush.c:318:  int length;
> common/usb_hub.c:613:   int i, length;
> 
> > You could avoid the subtraction instead of changing the type:
> >
> > -for (i = 0; i < presskey_max - 1; i++)
> > +for (i = 0; i + 1 < presskey_max; i++)
> This style seems not typically way for for loop, how do you think?
> 
> Best Regards
> Andy Wu
> 
> > -----Original Message-----
> > From: U-Boot <u-boot-bounces@lists.denx.de> On Behalf Of Heinrich
> > Schuchardt
> > Sent: Friday, January 15, 2021 8:19 PM
> > To: Mo, Yuezhang <Yuezhang.Mo@sony.com>; u-boot at lists.denx.de
> > Cc: sjg at chromium.org; hs at denx.de
> > Subject: Re: [PATCH] autoboot: fix illegal memory access when stop key
> > and delay key are empty
> >
> > On 15.01.21 04:11, Yuezhang.Mo at sony.com wrote:
> > > If both stop key and delay key are empty, the length of these keys
> > > is 0. The subtraction operation will cause the u_int type variable
> > > to overflow, will cause illegal memory access in key input loop.
> > >
> > > This commit fixes this bug by using int type instead of u_init.
> > > ---
> > >  common/autoboot.c | 6 +++---
> > >  1 file changed, 3 insertions(+), 3 deletions(-)
> > >
> > > diff --git a/common/autoboot.c b/common/autoboot.c index
> > > e628baffb8..61fb09f910 100644
> > > --- a/common/autoboot.c
> > > +++ b/common/autoboot.c
> > > @@ -156,9 +156,9 @@ static int passwd_abort_key(uint64_t etime)
> > >  	};
> > >
> > >  	char presskey[MAX_DELAY_STOP_STR];
> > > -	u_int presskey_len = 0;
> > > -	u_int presskey_max = 0;
> > > -	u_int i;
> > > +	int presskey_len = 0;
> > > +	int presskey_max = 0;
> >
> > Both indices cannot be negative. So it is understandable that u_int was chosen.
> > You could avoid the subtraction instead of changing the type:
> >
> > -for (i = 0; i < presskey_max - 1; i++)
> > +for (i = 0; i + 1 < presskey_max; i++)
> >
> > Acked-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
> >
> > > +	int i;
> > >
> > >  #  ifdef CONFIG_AUTOBOOT_DELAY_STR
> > >  	if (delaykey[0].str == NULL)
> > >