From owner-dev-commits-src-all@freebsd.org Mon Aug 16 19:18:05 2021
Return-Path: <owner-dev-commits-src-all@freebsd.org>
Delivered-To: dev-commits-src-all@mailman.nyi.freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1])
by mailman.nyi.freebsd.org (Postfix) with ESMTP id A6EDA6531AB;
Mon, 16 Aug 2021 19:18:05 +0000 (UTC) (envelope-from git@FreeBSD.org)
Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org
[IPv6:2610:1c1:1:606c::19:3])
(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256
client-signature RSA-PSS (4096 bits) client-digest SHA256)
(Client CN "mxrelay.nyi.freebsd.org", Issuer "R3" (verified OK))
by mx1.freebsd.org (Postfix) with ESMTPS id 4GpP7x3y9Jz3GCs;
Mon, 16 Aug 2021 19:18:05 +0000 (UTC) (envelope-from git@FreeBSD.org)
Received: from gitrepo.freebsd.org (gitrepo.freebsd.org
[IPv6:2610:1c1:1:6068::e6a:5])
(using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)
key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256)
(Client did not present a certificate)
by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 6D04670BE;
Mon, 16 Aug 2021 19:18:05 +0000 (UTC) (envelope-from git@FreeBSD.org)
Received: from gitrepo.freebsd.org ([127.0.1.44])
by gitrepo.freebsd.org (8.16.1/8.16.1) with ESMTP id 17GJI5HX090141;
Mon, 16 Aug 2021 19:18:05 GMT (envelope-from git@gitrepo.freebsd.org)
Received: (from git@localhost)
by gitrepo.freebsd.org (8.16.1/8.16.1/Submit) id 17GJI53J090140;
Mon, 16 Aug 2021 19:18:05 GMT (envelope-from git)
Date: Mon, 16 Aug 2021 19:18:05 GMT
Message-Id: <202108161918.17GJI53J090140@gitrepo.freebsd.org>
To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org,
dev-commits-src-main@FreeBSD.org
From: Mark Johnston <markj@FreeBSD.org>
Subject: git: c4feb1ab0ae0 - main - sigtimedwait: Use a unique wait channel
for sleeping
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 8bit
X-Git-Committer: markj
X-Git-Repository: src
X-Git-Refname: refs/heads/main
X-Git-Reftype: branch
X-Git-Commit: c4feb1ab0ae0c0e779af372e4c5f3b9e0d3e1388
Auto-Submitted: auto-generated
X-BeenThere: dev-commits-src-all@freebsd.org
X-Mailman-Version: 2.1.34
Precedence: list
List-Id: Commit messages for all branches of the src repository
<dev-commits-src-all.freebsd.org>
List-Unsubscribe: <https://lists.freebsd.org/mailman/options/dev-commits-src-all>,
<mailto:dev-commits-src-all-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/dev-commits-src-all/>
List-Post: <mailto:dev-commits-src-all@freebsd.org>
List-Help: <mailto:dev-commits-src-all-request@freebsd.org?subject=help>
List-Subscribe: <https://lists.freebsd.org/mailman/listinfo/dev-commits-src-all>,
<mailto:dev-commits-src-all-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Mon, 16 Aug 2021 19:18:05 -0000
The branch main has been updated by markj:
URL: https://cgit.FreeBSD.org/src/commit/?id=c4feb1ab0ae0c0e779af372e4c5f3b9e0d3e1388
commit c4feb1ab0ae0c0e779af372e4c5f3b9e0d3e1388
Author: Mark Johnston <markj@FreeBSD.org>
AuthorDate: 2021-08-16 17:15:25 +0000
Commit: Mark Johnston <markj@FreeBSD.org>
CommitDate: 2021-08-16 19:11:15 +0000
sigtimedwait: Use a unique wait channel for sleeping
When a sigtimedwait(2) caller goes to sleep, it uses a wait channel of
p->p_sigacts with the proc lock as the interlock. However, p_sigacts
can be shared between processes if a child is created with
rfork(RFSIGSHARE | RFPROC). Thus we can end up with two threads
sleeping on the same wait channel using different locks, which is not
permitted.
Fix the problem simply by using a process-unique wait channel, following
the example of sigsuspend. The actual wait channel value is irrelevant
here, sleeping threads are awoken using sleepq_abort().
Reported by: syzbot+8c417afabadb50bb8827@syzkaller.appspotmail.com
Reported by: syzbot+1d89fc2a9ef92ef64fa8@syzkaller.appspotmail.com
Reviewed by: kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D31563
---
sys/kern/kern_sig.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/sys/kern/kern_sig.c b/sys/kern/kern_sig.c
index 4f6f424fb05d..d61812ad3043 100644
--- a/sys/kern/kern_sig.c
+++ b/sys/kern/kern_sig.c
@@ -1341,7 +1341,8 @@ kern_sigtimedwait(struct thread *td, sigset_t waitset, ksiginfo_t *ksi,
break;
}
- error = msleep(ps, &p->p_mtx, PPAUSE|PCATCH, "sigwait", timo);
+ error = msleep(&p->p_sigacts, &p->p_mtx, PPAUSE | PCATCH,
+ "sigwait", timo);
/* The syscalls can not be restarted. */
if (error == ERESTART)