From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-171.sina.com.cn (smtp153-171.sina.com.cn [61.135.153.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 36E59DDAB for ; Fri, 27 Feb 2026 00:03:56 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772150643; cv=none; b=OjmzdRfAkiTW7lr1Z5f2yDXnrCQXmfquOmiFZX1GDEMedV3r0+8Xab9daZHp0/RMe/LpCHcsXCEBGvfGwVLuCtq4cmxJfeZEnT4a36BE8t1PKbKpqDypLSVoz2v0XyMbfxAb5SbydjUKE+3PYw84hARiCWfqe7ZtqU9YZyPjRm4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772150643; c=relaxed/simple; bh=HRe28VcS4LbmEseQonSCt7kICxrIs1ypCRJO3tU2NQU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=WufhLQKtK0z8+0phgOYkiTgVNebrPJVHtJoCmUemWq/MYrh8834QhXEh99cHvwO9ANAxcjQLQ66fvTaIniK+A+JqJiOq/ViDhx1RhI4AGao6WTfix5+7+0oU8+cTb3wHNXpWtf/F9DKbIfp6idtwO52H4o4K2Gv21FMoOsmTUNQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=0Sr6bvku; arc=none smtp.client-ip=61.135.153.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="0Sr6bvku" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1772150637; bh=xcwLUWWQMZFFkUo3dHYQU/5aaHsCKc1aqjMoXD1zp+k=; h=From:Subject:Date:Message-ID; b=0Sr6bvkuEhqHb8ZGedAyARwsWEi84SFmPUoF9WW5SbScinfe1CfMeFgCAj3HJCjeM sK12sCTI2UCAFqybL5PVwVk67H1ws1svN5A+9rxDJxEUhiB7oQZ/0wF1A1P2yRiZDU TS/NIOA5iSqTfSc7p6P/8CKHG/fz4UiO9FLru8uw= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.62.144]) by sina.com (10.54.253.34) with ESMTP id 69A0DF6000005D76; Fri, 27 Feb 2026 08:03:46 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 7152426291988 X-SMAIL-UIID: 8F4A1AD97E6A4074BF355FE1292D9B41-20260227-080346-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [kernel?] INFO: task hung in restrict_one_thread_callback Date: Fri, 27 Feb 2026 08:03:36 +0800 Message-ID: <20260227000337.553-1-hdanton@sina.com> In-Reply-To: <69984159.050a0220.21cd75.01bb.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit On Fri, Feb 20, 2026 at 03:11:21AM -0800 > Hello, > > syzbot found the following issue on: > > HEAD commit: 635c467cc14e Add linux-next specific files for 20260213 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=1452f6e6580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=61690c38d1398936 > dashboard link: https://syzkaller.appspot.com/bug?extid=7ea2f5e9dfd468201817 > compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=16e41c02580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15813652580000 #syz test upstream master --- x/security/landlock/tsync.c +++ y/security/landlock/tsync.c @@ -432,12 +432,17 @@ static void cancel_tsync_works(struct ts int landlock_restrict_sibling_threads(const struct cred *old_cred, const struct cred *new_cred) { + static int concur = 0; int err; struct tsync_shared_context shared_ctx; struct tsync_works works = {}; size_t newly_discovered_threads; bool found_more_threads; + if (concur++) { + concur--; + return -EBUSY; + } atomic_set(&shared_ctx.preparation_error, 0); init_completion(&shared_ctx.all_prepared); init_completion(&shared_ctx.ready_to_commit); @@ -556,6 +561,7 @@ int landlock_restrict_sibling_threads(co wait_for_completion(&shared_ctx.all_finished); tsync_works_release(&works); + concur--; return atomic_read(&shared_ctx.preparation_error); } --