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Message-ID: <5660A0DA.4070603@openwall.net>
Date: Thu, 3 Dec 2015 14:06:50 -0600
From: jfoug <jfoug@...nwall.net>
To: john-dev@...ts.openwall.com
Subject: Re: rules.c patch for ASan fault
How about this change:
diff --git a/src/rules.c b/src/rules.c
index 35cfe15..7eae64e 100644
--- a/src/rules.c
+++ b/src/rules.c
@@ -825,7 +825,7 @@ char *rules_apply(char *word, char *rule, int split,
char *last)
POSITION(mpos)
POSITION(count)
POSITION(ipos)
- mleft = (int)(rules_vars['m'] + 1) - mpos;
+ mleft = (int)((unsigned
char)(rules_vars['m'] + 1)) - mpos;
if (count > mleft)
count = mleft;
if (count <= 0)
On 12/3/2015 12:14 PM, magnum wrote:
> Solar,
>
> Here's a (maybe) proposed patch against john proper:
>
> diff --git a/src/rules.c b/src/rules.c
> index 35cfe15..7eae64e 100644
> --- a/src/rules.c
> +++ b/src/rules.c
> @@ -825,7 +825,7 @@ char *rules_apply(char *word, char *rule, int
> split, char *last)
> POSITION(mpos)
> POSITION(count)
> POSITION(ipos)
> - mleft = (int)(rules_vars['m'] + 1) -
> mpos;
> + mleft = (int)(rules_vars['l']) - mpos;
> if (count > mleft)
> count = mleft;
> if (count <= 0)
>
>
> This is within the 'X' command. The rationale is that rules_vars['m']
> is an unsigned char, initially set to (length - 1). When length is 0,
> rules_vars['m'] is thus 255. This leads to an ASan fault (at least a
> "read" fault) unless this patch is applied. There doesn't seem to be
> any more instance of similar problem.
>
> Is there some intended behavior that this patch would break? I can't
> imagine any.
>
> For background, see
> https://github.com/magnumripper/JohnTheRipper/issues/1744
>
> magnum
>
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