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 09:27:10 +0100 |
| commit | be95f1308f794861877af032bbb5b6ea48ca66a5 (patch) | |
| tree | 20179d47b2d61ee3ec4d9edf010457b79bd741b2 | |
| parent | 58330ec2fecd1c3a6b8759b292f32f82dfd058ba (diff) | |
| download | linux-rt-be95f1308f794861877af032bbb5b6ea48ca66a5.tar.gz | |
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 5d50ea899b6d..fc666bfd411a 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); } /* |