From: Eric W. Biederman <ebiederm@xmission.com>
Date: Mon, 24 Jul 2017 19:53:03 +0000 (-0500)
Subject: signal: Clear si_sys_private before copying siginfo to userspace
X-Git-Tag: Ubuntu-5.10.0-12.13~8569^2~27
X-Git-Url: https://git.proxmox.com/?a=commitdiff_plain;h=9943d3accb4ec5a85e72c65a9959257fa7d12500;p=mirror_ubuntu-hirsute-kernel.git

signal: Clear si_sys_private before copying siginfo to userspace

In preparation for unconditionally copying the whole of siginfo
to userspace clear si_sys_private.  So this kernel internal
value is guaranteed not to make it to userspace.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
---

diff --git a/kernel/signal.c b/kernel/signal.c
index b9e5d825ee46..18aa55c1bb4f 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -643,6 +643,9 @@ int dequeue_signal(struct task_struct *tsk, sigset_t *mask, siginfo_t *info)
 		spin_unlock(&tsk->sighand->siglock);
 		posixtimer_rearm(info);
 		spin_lock(&tsk->sighand->siglock);
+
+		/* Don't expose the si_sys_private value to userspace */
+		info->si_sys_private = 0;
 	}
 #endif
 	return signr;