linux-kernel - %e in /proc/sys/kernel/core_pattern and empty current->comm

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Message-ID: <4E5A7094.90202@ixiacom.com>
Date:	Sun, 28 Aug 2011 09:45:08 -0700
From:	Earl Chew <echew@...acom.com>
To:	<linux-kernel@...r.kernel.org>
Subject: %e in /proc/sys/kernel/core_pattern and empty current->comm

It is possible to set /proc/sys/kernel/core_pattern to %e:

	echo '%e' > /proc/sys/kernel/core_pattern

A couple of interesting effects:

a. Cores will tend to try to overwrite the executable.

    Is this considered an issue ?

b. Apparently it seems possible to set current->comm to be empty:

	prctl(PR_SET_NAME, "", 0, 0, 0);

   No core dump is generated since the resulting corename is empty,
   and filp_open() fails.

   Is this considered a defect, or potential security concern ?

c. Consequential to (b), setting /proc/sys/kernel/core_pattern to empty
   and /proc/sys/kernel/core_uses_pid to zero universally prevents
   core dumps.

   I'm wondering if this behaviour is provided intentionally.

Earl

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