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=1793831409; b=Fl6R3Er4pQg9gzXSxndbjbP+Af0mfh2gtG34i3qsCX6wWsfurKXdVmfN41UqSGUS8lxb U9rMApqouFmIXJxnfmG383eJ1odw77V7fUecXeYw0ARRLxe1MPosICWhpovcq9/Go83hw w303Al036kGPdUAkA17GzebRYH8noAu6j3C7j6CwEeIniuDSP4iJ1Tzmrj8Wr2M8DOvKc k6ITXvYbMLZuzUKNePtOx9Wk92uoG54Nel1MxmS+v0lPRfbmiToZ57gTKUNuGvfETkK1v 671QMeKiHPfYCq5zB5mEOZgzQ8VPxxO6RAszPKtK70vCmS+jrdPmbAn8yZVbqlwJiQg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1793831409; 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=eSFvcr40OXL6doj4QipvJMXoK3Nc23D6gmo36IwOAPo=; b=leBzb0T+gBGZhfXijjAyyQLNr99tQsKZy0nctsj9rE+KArP8hv2gwTnQ1KumPb2CKt1H e/A3LbqDSBSFfJYoEhVbgA+4WP8IM0eumD5TdIGd8RY1SXDgydG+T8a++oJoMY+66SNB2 OSS1CcOKn64buaPXkbDT45K+oizmR7rbFoGDCNW0pbhLgXFl5xS0B0rPIP8dAOsm9SlEG MQ7El0ESZqQ5JMHS0mfHAGrUG19b7nsUon4nz4IGpGaRaOw8QxsjDJVq2sO/f6HQsuhLN 9dtqCLY36xk0CanJ5UPKIFt52SEAxHzONEvDPsryX1pl1Cm82m7Y3HQ1p5j7nBdE2eQ== 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=xltLbKLy; 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 44D7D606AB29; Wed, 4 Nov 2026 22:30:09 +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=xltLbKLy Received: by smtp.kernel.org (Postfix) with ESMTPSA id D434E1F00919; Wed, 4 Nov 2026 22:30:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1793831409; bh=eSFvcr40OXL6doj4QipvJMXoK3Nc23D6gmo36IwOAPo=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=xltLbKLyh5lbB2WhmZ93QmKL6iC9UNRZGByHMnlOXZ7bYN4dC2GMp3Uc/4KAK+B+M cXfFhF+NFlslJDQPIzGOSOWmPiDdPC/8MrQqJPlX+RqUy2wCz6/oVkgplSNzqP7Rh6 r+fJskRLKaZ6CQ6opnU9LVCvH/ZJXy8cWqTtLW6I= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Heiko Carstens Subject: [PATCH 6.18 0688/1005] s390/signal: Fix incorrect return address in signal frame Date: Wed, 4 Nov 2026 16:07:01 -0500 Message-ID: <20261104211102.888241985@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261104211043.516122098@linuxfoundation.org> References: <20261104211043.516122098@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: Heiko Carstens commit adc9e872f7350e3ac29c1818d8c68b0760b4ba23 upstream. exit_to_user_mode_loop() can call arch_do_signal_or_restart() multiple times when signals are pending. If the first call set up a vDSO system call restart by saving the real user return address and adjusting psw.addr so it points to the vDSO stub, a second call builds the signal frame with the wrong return address. Restore psw.addr from arch_data, and set the return code to -EINTR before building the signal frame. This requires restart_block.arch_data to be properly initialized for all tasks. Move the initialization in copy_thread() in front of the kernel thread check, so that it also covers kernel threads and their children (PID 1, usermode helpers). Only PID 0 is left uninitialized, since it never returns to user space. Fixes: df29a7440c4b ("s390/signal: switch to using vdso for sigreturn and syscall restart") Cc: stable@vger.kernel.org Signed-off-by: Heiko Carstens Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/process.c | 12 ++++++------ arch/s390/kernel/signal.c | 6 +++++- 2 files changed, 11 insertions(+), 7 deletions(-) --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -132,6 +132,12 @@ int copy_thread(struct task_struct *p, c p->thread.hardirq_timer = 0; p->thread.softirq_timer = 0; p->thread.last_break = 1; + /* + * s390 stores the svc return address in arch_data when calling + * sigreturn()/restart_syscall() via vdso. 1 means no valid address + * stored. + */ + p->restart_block.arch_data = 1; frame->sf.back_chain = 0; frame->sf.gprs[11 - 6] = (unsigned long)&frame->childregs; @@ -173,12 +179,6 @@ int copy_thread(struct task_struct *p, c p->thread.acrs[1] = (unsigned int)tls; } } - /* - * s390 stores the svc return address in arch_data when calling - * sigreturn()/restart_syscall() via vdso. 1 means no valid address - * stored. - */ - p->restart_block.arch_data = 1; return 0; } --- a/arch/s390/kernel/signal.c +++ b/arch/s390/kernel/signal.c @@ -488,7 +488,11 @@ void arch_do_signal_or_restart(struct pt } /* No longer in a system call */ clear_pt_regs_flag(regs, PIF_SYSCALL); - + if (!(current->restart_block.arch_data & 1)) { + regs->psw.addr = current->restart_block.arch_data; + current->restart_block.arch_data = 1; + regs->gprs[2] = -EINTR; + } rseq_signal_deliver(&ksig, regs); if (is_compat_task()) handle_signal32(&ksig, oldset, regs);