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authorKees Cook <keescook@chromium.org>2022-02-08 00:57:17 -0800
committerKees Cook <keescook@chromium.org>2022-02-10 19:08:54 -0800
commit5c72263ef2fbe99596848f03758ae2dc593adf2c (patch)
tree60249a1e125168780858cad5f5cebb87338f49ed
parent26291c54e111ff6ba87a164d85d4a4e134b7315c (diff)
signal: HANDLER_EXIT should clear SIGNAL_UNKILLABLE
Fatal SIGSYS signals (i.e. seccomp RET_KILL_* syscall filter actions) were not being delivered to ptraced pid namespace init processes. Make sure the SIGNAL_UNKILLABLE doesn't get set for these cases. Reported-by: Robert Święcki <robert@swiecki.net> Suggested-by: "Eric W. Biederman" <ebiederm@xmission.com> Fixes: 00b06da29cf9 ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed") Cc: stable@vger.kernel.org Signed-off-by: Kees Cook <keescook@chromium.org> Reviewed-by: "Eric W. Biederman" <ebiederm@xmission.com> Link: https://lore.kernel.org/lkml/878rui8u4a.fsf@email.froward.int.ebiederm.org
-rw-r--r--kernel/signal.c5
1 files changed, 3 insertions, 2 deletions
diff --git a/kernel/signal.c b/kernel/signal.c
index 38602738866e..9b04631acde8 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -1342,9 +1342,10 @@ force_sig_info_to_task(struct kernel_siginfo *info, struct task_struct *t,
}
/*
* Don't clear SIGNAL_UNKILLABLE for traced tasks, users won't expect
- * debugging to leave init killable.
+ * debugging to leave init killable. But HANDLER_EXIT is always fatal.
*/
- if (action->sa.sa_handler == SIG_DFL && !t->ptrace)
+ if (action->sa.sa_handler == SIG_DFL &&
+ (!t->ptrace || (handler == HANDLER_EXIT)))
t->signal->flags &= ~SIGNAL_UNKILLABLE;
ret = send_signal(sig, info, t, PIDTYPE_PID);
spin_unlock_irqrestore(&t->sighand->siglock, flags);