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List: oss-security
Subject: [oss-security] CVE-2009-1388 kernel: do_coredump() vs ptrace_start() deadlock
From: Eugene Teo <eugene () redhat ! com>
Date: 2009-07-02 12:40:27
Message-ID: 4A4CAABB.8030407 () redhat ! com
[Download RAW message or body]
The OpenVZ Linux kernel team has found deadlock between ptrace and
coredump code. It affects 2.6.18 but does not affect the upstream kernel.
"ptrace_start() spins waiting for child->state ==
TASK_TRACED/TASK_STOPPED. If we race with the coredumping, we have to
wait until it completes.
If the tracer participates in coredumping too, we deadlock.
do_coredump() waits for tracer to exit and report
complete(mm->core_startup_done), the tracer spins in an endless loop.
Change ptrace_start() to abort if child->mm->core_waiters != 0."
Patch:
https://bugzilla.redhat.com/attachment.cgi?id=346742
Reference:
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2009-1388
Thanks, Eugene
--
Eugene Teo / Red Hat Security Response Team
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