From: Szabolcs Nagy <nsz@port70.net>
To: musl@lists.openwall.com
Subject: Re: [PATCH] Add support for mkostemp, mkstemps and mkostemps
Date: Sat, 2 Feb 2013 23:22:33 +0100 [thread overview]
Message-ID: <20130202222233.GN6181@port70.net> (raw)
In-Reply-To: <510D7953.50308@opensource.dyc.edu>
* Anthony G. Basile <basile@opensource.dyc.edu> [2013-02-02 15:38:43 -0500]:
> 2. This is from uclibc. Clearly, static is critical here, but still
> they never initialize a value of 'value' on first entry into the
> function, so that memory is dirty to start. Mine is worse, but I
> wonder if this is still a bug there.
>
> static void brain_damaged_fillrand(unsigned char *buf, unsigned int len)
> {
> ...
> static uint64_t value;
> gettimeofday(&tv, NULL);
> value += ((uint64_t) tv.tv_usec << 16) ^ tv.tv_sec ^ getpid();
> ...
static variables are always initialized to 0
they use static so every call to that function
uses some entropy from the previous call
(in multithreaded code it may not work that way)
> 3. I retested your address approach. I like it but it only maps to
> upper and lower case letters, no numbers which uclibc and glibc do.
yes i used 6*5 bit for the names, which makes sense: r is 32bits usually
(ie. that code can generate 2^30 different names)
uclibc/glibc can generate 62^6 names (about 2^36) which is a bit more
but by not much
> clock_gettime(CLOCK_REALTIME, &ts);
> r = ts.tv_nsec*65537 ^ (uintptr_t)&ts / 16 + (uintptr_t)template;
> for (i=0; i<6; i++, r>>=5)
> template[i] = 'A'+(r&15)+(r&16)*2;
>
next prev parent reply other threads:[~2013-02-02 22:22 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-02-02 18:45 Anthony G. Basile
2013-02-02 19:51 ` John Spencer
2013-02-02 19:59 ` John Spencer
2013-02-02 22:11 ` Szabolcs Nagy
2013-02-02 20:14 ` Szabolcs Nagy
2013-02-02 20:38 ` Anthony G. Basile
2013-02-02 22:22 ` Szabolcs Nagy [this message]
-- strict thread matches above, loose matches on Subject: below --
2013-02-02 21:15 Anthony G. Basile
2013-02-02 21:17 ` Anthony G. Basile
2013-02-03 3:30 ` Rich Felker
2013-01-28 5:06 Anthony G. Basile
2013-01-28 8:47 ` John Spencer
2013-01-28 9:37 ` Szabolcs Nagy
2013-01-28 17:33 ` Szabolcs Nagy
2013-01-29 23:16 ` Anthony G. Basile
2013-01-30 7:21 ` Rich Felker
2013-01-30 7:59 ` Hardy Falk
2013-01-30 13:45 ` Szabolcs Nagy
2013-01-30 16:51 ` Rich Felker
2013-01-30 19:12 ` Szabolcs Nagy
2013-01-30 19:22 ` Rich Felker
2013-01-31 0:28 ` Szabolcs Nagy
2013-01-28 16:33 ` Rich Felker
2013-02-02 3:48 ` Rich Felker
2013-02-02 18:46 ` Anthony G. Basile
2013-01-28 2:36 Anthony G. Basile
2013-01-28 5:01 ` Anthony G. Basile
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