From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1793209860; b=uuMlC6X1C3k+WouYfYgXbCzapFFh6Ku2IkD6zQXXr4r0t5jmE7e9ylQBJcta7gLYBXkJ wP+2Jf+H7jT/YpFHHrOtcheMexCI7vWF962FQG4kWbyv6F4yd4YUBi2hI+soGLgwzjNAY CKtjgoW4uK891KSs0MhwKKjvUXQbGKu+gwCHF61/aHJbM6zyeXYLxloyZuvrgIWL6TRY7 fg0nltXvoEwH01YZDjUQSeGh/4QbCvB0AtXwTmnB9oPi8+sdVrb/hmDE/3OrVMRmOOPL0 5o8xe+sQcg+8ZbNMkx9v8qjSSHGN+egJzd13JNB0Jie7tA6WWX8UHnGfkxN/vjv5Dlw== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793209860; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=HZYF2x87JV27cQWcNZVUwTWk+72ITmF+64eDZU8nLDY=; b=kCavWx/s2HynzpRFNnszi5X/13dagfzRBSneEN7VktDwoeWUP4/Sejkwenv0ToEfsTC1 YWAsZZ1Yf6xyA+iYU9yVFov6+KD/2rxnskiMLrTweVPOT9Plhq3337a86s95JOFJLxIP+ Mvr794tSEU+zRYFP7kWnGpZynTqKAOOlMwEO6T3uQrvCB2iRlsb/IWqUIngxH0jqu0q5A qxmuzZYIC/rNjM9QzSEAb+hMA1djfxDf+GzZAqIsEKoqvhe5EHygfftykmgkC/O7jgoUg JHhN9yT4O85W1m23wWWNRSshR4XABB1EpWuhhe7/TSWdAZTj0TN25OJxx+OZ/NPWSBQ== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=c0N1S+0P; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B9A4C606A31D; Wed, 28 Oct 2026 17:50:59 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=c0N1S+0P Received: by smtp.kernel.org (Postfix) with ESMTPSA id 163061F01825; Wed, 28 Oct 2026 17:50:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793209859; bh=HZYF2x87JV27cQWcNZVUwTWk+72ITmF+64eDZU8nLDY=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=c0N1S+0P2wTRrWDCOlT6xcE72w9uGMjUTKwfdxS3EHIGkz1DLxUAtOqDoDfZVsyiJ 0bdg8Uho3XdrG8pMcV7TbdTOOBlCGu5ULMrST4c94Ntx5wM02jyVkCD8Byf+9ePF24 a4hBCQIkKOpQ55FGcgUxF2RPbwf2rEDdQmwslK3A= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Oleg Nesterov , "Christian Brauner (Amutable)" Subject: [PATCH 6.18 103/109] signal: dont retarget shared signals in a dying thread group Date: Wed, 28 Oct 2026 18:01:27 +0100 Message-ID: <20261028165944.780504280@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261028165942.357251485@linuxfoundation.org> References: <20261028165942.357251485@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Christian Brauner commit c0e659511d4f49087da095a95799edb5b775a705 upstream. If the calling thread has blocked a signal then retarget_shared_pending() slingshots a shared pending signal to a sibling thread. Today it only skips PF_EXITING threads but not a coredumping thread. But if SIGNAL_GROUP_EXIT is set no thread in the thread-group can dequeue such signals anymore as get_signal() sends SIGKILL to every thread and prepare_signal() drops any other signal. exit_signals() also returns early on SIGNAL_GROUP_EXIT. But neither sigprocmask() nor the mask restore in sigtimedwait() do. Say a thread sleeps in sigtimedwait() and a sibling thread crashes. The sleeping thread gets woken by the zap call. It restores its mask on the way out and retargets a signal that was queued for the coredumping process. That means TIF_SIGPENDING is set on the coredumping task which zap_threads() had cleared. So a blocking write sees TIF_SIGPENDING and truncates the dump. Stop retargeting signals when SIGNAL_GROUP_EXIT is set and avoid needlessly truncating coredumps. Fixes: e6fa16ab9c1e ("signal: sigprocmask() should do retarget_shared_pending()") Cc: stable@vger.kernel.org Acked-by: Oleg Nesterov Link: https://patch.msgid.link/20260921-work-coredump-fixes-v3-5-8e4adb1619e6@kernel.org Signed-off-by: Christian Brauner (Amutable) Signed-off-by: Greg Kroah-Hartman --- kernel/signal.c | 4 ++++ 1 file changed, 4 insertions(+) --- a/kernel/signal.c +++ b/kernel/signal.c @@ -3178,6 +3178,10 @@ static void retarget_shared_pending(stru sigset_t retarget; struct task_struct *t; + /* Nobody dequeues them in a dying group, see get_signal(). */ + if (tsk->signal->flags & SIGNAL_GROUP_EXIT) + return; + sigandsets(&retarget, &tsk->signal->shared_pending.signal, which); if (sigisemptyset(&retarget)) return;