From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6515DC636CE for ; Thu, 15 Jul 2021 19:18:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4820C613D4 for ; Thu, 15 Jul 2021 19:18:09 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244890AbhGOTU7 (ORCPT ); Thu, 15 Jul 2021 15:20:59 -0400 Received: from mail.kernel.org ([198.145.29.99]:58962 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S245064AbhGOTTP (ORCPT ); Thu, 15 Jul 2021 15:19:15 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4EAEA613F2; Thu, 15 Jul 2021 19:14:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626376442; bh=5JIVYpka/8B06HYh8T3fYIDyW9P6b7DJtITXlW+WJeo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=EMkWkl/9B8DLjDz2ykB7x2Y01zoq55NhnrcXRy6+2vTAID/uB9iOgMR6q31aR0xrQ 93mYtjVcUhmdH745gcKB9sIXPif3Hy+pEv3Rq/fwrJycsfyogeHginNy+0QBLspigF pLSVscQVkXo4QiIPMaFGlu91FVTxI7YMaviXoOR0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sven Schnelle , Heiko Carstens , Vasily Gorbik , stable@kernel.org Subject: [PATCH 5.13 258/266] s390/signal: switch to using vdso for sigreturn and syscall restart Date: Thu, 15 Jul 2021 20:40:13 +0200 Message-Id: <20210715182652.859757404@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210715182613.933608881@linuxfoundation.org> References: <20210715182613.933608881@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Sven Schnelle commit df29a7440c4b5c65765c8f60396b3b13063e24e9 upstream. with generic entry, there's a bug when it comes to restarting of signals. The failing sequence is: a) a signal is coming in, and no handler is registered, so the lower part of arch_do_signal_or_restart() in arch/s390/kernel/signal.c sets PIF_SYSCALL_RESTART. b) a second signal gets pending while the kernel is still in the exit loop, and for that one, a handler exists. c) The first part of arch_do_signal_or_restart() is called. That part calls handle_signal(), which sets up stack + registers for handling the signal. d) __do_syscall() in arch/s390/kernel/syscall.c checks for PIF_SYSCALL_RESTART right before leaving to userspace. If it is set, it restart's the syscall. However, the registers are already setup for handling a signal from c). The syscall is now restarted with the wrong arguments. Change the code to: - use vdso for syscall_restart() instead of PIF_SYSCALL_RESTART because we cannot rewind and go back to userspace on s390 because the system call number might be encoded in the svc instruction. - for all other syscalls we rewind the PSW and return to userspace. Cc: # v5.12+ d57778feb987: s390/vdso: always enable vdso Cc: # v5.12+ 686341f2548b: s390/vdso64: add sigreturn,rt_sigreturn and restart_syscall Cc: # v5.12+ 43e1f76b0b69: s390/vdso: rename VDSO64_LBASE to VDSO_LBASE Cc: # v5.12+ 779df2248739: s390/vdso: add minimal compat vdso Cc: # v5.12+ Signed-off-by: Sven Schnelle Reviewed-by: Heiko Carstens Signed-off-by: Vasily Gorbik Signed-off-by: Greg Kroah-Hartman --- arch/s390/kernel/compat_signal.c | 13 +++---------- arch/s390/kernel/process.c | 6 ++++++ arch/s390/kernel/signal.c | 39 ++++++++++++++++++--------------------- arch/s390/kernel/syscall.c | 4 ++++ 4 files changed, 31 insertions(+), 31 deletions(-) --- a/arch/s390/kernel/compat_signal.c +++ b/arch/s390/kernel/compat_signal.c @@ -28,6 +28,7 @@ #include #include #include +#include #include "compat_linux.h" #include "compat_ptrace.h" #include "entry.h" @@ -118,7 +119,6 @@ static int restore_sigregs32(struct pt_r fpregs_load((_s390_fp_regs *) &user_sregs.fpregs, ¤t->thread.fpu); clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */ - clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART); return 0; } @@ -304,11 +304,7 @@ static int setup_frame32(struct ksignal restorer = (unsigned long __force) ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE; } else { - /* Signal frames without vectors registers are short ! */ - __u16 __user *svc = (void __user *) frame + frame_size - 2; - if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc)) - return -EFAULT; - restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE; + restorer = VDSO32_SYMBOL(current, sigreturn); } /* Set up registers for signal handler */ @@ -371,10 +367,7 @@ static int setup_rt_frame32(struct ksign restorer = (unsigned long __force) ksig->ka.sa.sa_restorer | PSW32_ADDR_AMODE; } else { - __u16 __user *svc = &frame->svc_insn; - if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc)) - return -EFAULT; - restorer = (unsigned long __force) svc | PSW32_ADDR_AMODE; + restorer = VDSO32_SYMBOL(current, rt_sigreturn); } /* Create siginfo on the signal stack */ --- a/arch/s390/kernel/process.c +++ b/arch/s390/kernel/process.c @@ -166,6 +166,12 @@ int copy_thread(unsigned long clone_flag 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 @@ -32,6 +32,7 @@ #include #include #include +#include #include "entry.h" /* @@ -171,7 +172,6 @@ static int restore_sigregs(struct pt_reg fpregs_load(&user_sregs.fpregs, ¤t->thread.fpu); clear_pt_regs_flag(regs, PIF_SYSCALL); /* No longer in a system call */ - clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART); return 0; } @@ -334,15 +334,10 @@ static int setup_frame(int sig, struct k /* Set up to return from userspace. If provided, use a stub already in userspace. */ - if (ka->sa.sa_flags & SA_RESTORER) { + if (ka->sa.sa_flags & SA_RESTORER) restorer = (unsigned long) ka->sa.sa_restorer; - } else { - /* Signal frame without vector registers are short ! */ - __u16 __user *svc = (void __user *) frame + frame_size - 2; - if (__put_user(S390_SYSCALL_OPCODE | __NR_sigreturn, svc)) - return -EFAULT; - restorer = (unsigned long) svc; - } + else + restorer = VDSO64_SYMBOL(current, sigreturn); /* Set up registers for signal handler */ regs->gprs[14] = restorer; @@ -397,14 +392,10 @@ static int setup_rt_frame(struct ksignal /* Set up to return from userspace. If provided, use a stub already in userspace. */ - if (ksig->ka.sa.sa_flags & SA_RESTORER) { + if (ksig->ka.sa.sa_flags & SA_RESTORER) restorer = (unsigned long) ksig->ka.sa.sa_restorer; - } else { - __u16 __user *svc = &frame->svc_insn; - if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn, svc)) - return -EFAULT; - restorer = (unsigned long) svc; - } + else + restorer = VDSO64_SYMBOL(current, rt_sigreturn); /* Create siginfo on the signal stack */ if (copy_siginfo_to_user(&frame->info, &ksig->info)) @@ -501,7 +492,7 @@ void arch_do_signal_or_restart(struct pt } /* No longer in a system call */ clear_pt_regs_flag(regs, PIF_SYSCALL); - clear_pt_regs_flag(regs, PIF_SYSCALL_RESTART); + rseq_signal_deliver(&ksig, regs); if (is_compat_task()) handle_signal32(&ksig, oldset, regs); @@ -517,14 +508,20 @@ void arch_do_signal_or_restart(struct pt switch (regs->gprs[2]) { case -ERESTART_RESTARTBLOCK: /* Restart with sys_restart_syscall */ - regs->int_code = __NR_restart_syscall; - fallthrough; + regs->gprs[2] = regs->orig_gpr2; + current->restart_block.arch_data = regs->psw.addr; + if (is_compat_task()) + regs->psw.addr = VDSO32_SYMBOL(current, restart_syscall); + else + regs->psw.addr = VDSO64_SYMBOL(current, restart_syscall); + if (test_thread_flag(TIF_SINGLE_STEP)) + clear_thread_flag(TIF_PER_TRAP); + break; case -ERESTARTNOHAND: case -ERESTARTSYS: case -ERESTARTNOINTR: - /* Restart system call with magic TIF bit. */ regs->gprs[2] = regs->orig_gpr2; - set_pt_regs_flag(regs, PIF_SYSCALL_RESTART); + regs->psw.addr = __rewind_psw(regs->psw, regs->int_code >> 16); if (test_thread_flag(TIF_SINGLE_STEP)) clear_thread_flag(TIF_PER_TRAP); break; --- a/arch/s390/kernel/syscall.c +++ b/arch/s390/kernel/syscall.c @@ -121,6 +121,10 @@ void do_syscall(struct pt_regs *regs) regs->gprs[2] = nr; + if (nr == __NR_restart_syscall && !(current->restart_block.arch_data & 1)) { + regs->psw.addr = current->restart_block.arch_data; + current->restart_block.arch_data = 1; + } nr = syscall_enter_from_user_mode_work(regs, nr); /*