kernel/signal.c: protect the traced SIGNAL_UNKILLABLE tasks from SIGKILL
commit 628c1bcba2
upstream.
The comment in sig_ignored() says "Tracers may want to know about even
ignored signals" but SIGKILL can not be reported to debugger and it is
just wrong to return 0 in this case: SIGKILL should only kill the
SIGNAL_UNKILLABLE task if it comes from the parent ns.
Change sig_ignored() to ignore ->ptrace if sig == SIGKILL and rely on
sig_task_ignored().
SISGTOP coming from within the namespace is not really right too but at
least debugger can intercept it, and we can't drop it here because this
will break "gdb -p 1": ptrace_attach() won't work. Perhaps we will add
another ->ptrace check later, we will see.
Link: http://lkml.kernel.org/r/20171103184206.GB21036@redhat.com
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Tested-by: Kyle Huey <me@kylehuey.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
pull/10/head
parent
22af48be82
commit
2ebd69e8c2
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@ -94,13 +94,15 @@ static int sig_ignored(struct task_struct *t, int sig, bool force)
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if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig))
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return 0;
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if (!sig_task_ignored(t, sig, force))
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/*
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* Tracers may want to know about even ignored signal unless it
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* is SIGKILL which can't be reported anyway but can be ignored
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* by SIGNAL_UNKILLABLE task.
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*/
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if (t->ptrace && sig != SIGKILL)
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return 0;
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/*
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* Tracers may want to know about even ignored signals.
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*/
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return !t->ptrace;
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return sig_task_ignored(t, sig, force);
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}
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/*
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