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@sony.com Sent: Monday, January 18, 2021 1:22 PM To: xypron.glpk@gmx.de; Mo, Yuezhang Yuezhang.Mo@sony.com; u-boot@lists.denx.de Cc: sjg@chromium.org; hs@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@lists.denx.de Cc: sjg@chromium.org; hs@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@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)