From: Valdis.Kletnieks@vt.edu
To: Chase Douglas <chase.douglas@canonical.com>
Cc: Steven Rostedt <srostedt@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] trace-cmd: prevent print_graph_duration buffer overflow
Date: Sun, 13 Jun 2010 16:52:53 -0400 [thread overview]
Message-ID: <40245.1276462373@localhost> (raw)
In-Reply-To: Your message of "Sun, 13 Jun 2010 13:11:48 EDT." <1276449108-21328-2-git-send-email-chase.douglas@canonical.com>
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On Sun, 13 Jun 2010 13:11:48 EDT, Chase Douglas said:
> Passing n > sizeof(string) to snprintf can cause a glibc buffer overflow
> condition. We know the exact size of nsecs_str, so use it instead of
> math that may overflow.
> /* Print nsecs (we don't want to exceed 7 numbers) */
> if ((s->len - len) < 7) {
> - snprintf(nsecs_str, 8 - (s->len - len), "%03lu", nsecs_rem);
> + snprintf(nsecs_str, sizeof(nsecs_str), "%03lu", nsecs_rem);
We only get into this code after we've checked that the length is under 7
characters. How much overflow can happen as long as the sizeof(nsecs_str) is a
sane size (like at least 8 chars)? Probably a better bet would be doing the
right thing and 'BUILD_BUG_ON(sizeof(nsecs_str) < 8);'?
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next prev parent reply other threads:[~2010-06-13 20:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-06-13 17:11 [PATCH] trace-cmd: append to CFLAGS instead of being overriden Chase Douglas
2010-06-13 17:11 ` [PATCH] trace-cmd: prevent print_graph_duration buffer overflow Chase Douglas
2010-06-13 20:52 ` Valdis.Kletnieks [this message]
2010-06-13 21:01 ` Chase Douglas
2010-06-14 21:40 ` Valdis.Kletnieks
2010-06-15 0:16 ` Steven Rostedt
2010-06-15 12:49 ` Frederic Weisbecker
2010-06-15 13:04 ` Chase Douglas
2010-06-15 13:10 ` Frederic Weisbecker
2010-06-15 13:20 ` Chase Douglas
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