diff options
| author | Oleg Nesterov <oleg@redhat.com> | 2017-11-17 15:30:01 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2018-01-10 09:29:52 +0100 |
| commit | 1453b3ac6cf8c62abb5a50680c6626d460c63044 (patch) | |
| tree | 25833d9f68bfe0f6d4d91f3a1c9d6a788c6c32f4 | |
| parent | 79258d9834803518a80b0ed0603c790638f0478b (diff) | |
kernel/signal.c: protect the traced SIGNAL_UNKILLABLE tasks from SIGKILL
commit 628c1bcba204052d19b686b5bac149a644cdb72e 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>
| -rw-r--r-- | kernel/signal.c | 12 |
1 files changed, 7 insertions, 5 deletions
diff --git a/kernel/signal.c b/kernel/signal.c index e48668c3c972..107ce6a4832d 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -88,13 +88,15 @@ static int sig_ignored(struct task_struct *t, int sig, bool force) if (sigismember(&t->blocked, sig) || sigismember(&t->real_blocked, sig)) return 0; - if (!sig_task_ignored(t, sig, force)) - return 0; - /* - * Tracers may want to know about even ignored signals. + * Tracers may want to know about even ignored signal unless it + * is SIGKILL which can't be reported anyway but can be ignored + * by SIGNAL_UNKILLABLE task. */ - return !t->ptrace; + if (t->ptrace && sig != SIGKILL) + return 0; + + return sig_task_ignored(t, sig, force); } /* |