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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 F1DD7C433DF for ; Tue, 23 Jun 2020 17:35:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D1B4920781 for ; Tue, 23 Jun 2020 17:35:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592933751; bh=aZX3bH4RlKLW5bh/pndxC1n7t5/JBse0G0JucZ29OCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=Arzb2hbyiu3EvRxSNGrZiltyexjMWoqImOq9aKRPZripuo5nsml/dT0EN8SNV5Sjo 9ml+cm+ul5Fb3QxVKpE2XQO9YhfZ7YtHD7WyzgT7YkSxKpgU2hBXerhnNC5726d6tA /GCLfULOWY2oSVJptW0SITuJJmBRBVkVPdLGunjI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1733308AbgFWRfu (ORCPT ); Tue, 23 Jun 2020 13:35:50 -0400 Received: from mail.kernel.org ([198.145.29.99]:60442 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1733280AbgFWRfq (ORCPT ); Tue, 23 Jun 2020 13:35:46 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id DCC32207E8; Tue, 23 Jun 2020 17:35:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1592933745; bh=aZX3bH4RlKLW5bh/pndxC1n7t5/JBse0G0JucZ29OCg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=wHrosRsaFvntgFftkR171vwvOg1HhPV6/quVRqfQG9xEbWRusytnD17XDDBx1CsDv d+m9VEWdap7RAV6zcimATQapIy80wuyOxX8im5TXUNs9NNq01T5lYJ1WknxBVOsW2A 0HFQgklg5qxNZxPelTjO3ZdNMNwnHzylU/+3Ct5o= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sven Schnelle , Vasily Gorbik , Sasha Levin , linux-s390@vger.kernel.org Subject: [PATCH AUTOSEL 5.7 18/28] s390/ptrace: fix setting syscall number Date: Tue, 23 Jun 2020 13:35:13 -0400 Message-Id: <20200623173523.1355411-18-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200623173523.1355411-1-sashal@kernel.org> References: <20200623173523.1355411-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sven Schnelle [ Upstream commit 873e5a763d604c32988c4a78913a8dab3862d2f9 ] When strace wants to update the syscall number, it sets GPR2 to the desired number and updates the GPR via PTRACE_SETREGSET. It doesn't update regs->int_code which would cause the old syscall executed on syscall restart. As we cannot change the ptrace ABI and don't have a field for the interruption code, check whether the tracee is in a syscall and the last instruction was svc. In that case assume that the tracer wants to update the syscall number and copy the GPR2 value to regs->int_code. Signed-off-by: Sven Schnelle Signed-off-by: Vasily Gorbik Signed-off-by: Sasha Levin --- arch/s390/kernel/ptrace.c | 31 ++++++++++++++++++++++++++++++- 1 file changed, 30 insertions(+), 1 deletion(-) diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c index fca78b269349d..e007224b65bb2 100644 --- a/arch/s390/kernel/ptrace.c +++ b/arch/s390/kernel/ptrace.c @@ -324,6 +324,25 @@ static inline void __poke_user_per(struct task_struct *child, child->thread.per_user.end = data; } +static void fixup_int_code(struct task_struct *child, addr_t data) +{ + struct pt_regs *regs = task_pt_regs(child); + int ilc = regs->int_code >> 16; + u16 insn; + + if (ilc > 6) + return; + + if (ptrace_access_vm(child, regs->psw.addr - (regs->int_code >> 16), + &insn, sizeof(insn), FOLL_FORCE) != sizeof(insn)) + return; + + /* double check that tracee stopped on svc instruction */ + if ((insn >> 8) != 0xa) + return; + + regs->int_code = 0x20000 | (data & 0xffff); +} /* * Write a word to the user area of a process at location addr. This * operation does have an additional problem compared to peek_user. @@ -335,7 +354,9 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data) struct user *dummy = NULL; addr_t offset; + if (addr < (addr_t) &dummy->regs.acrs) { + struct pt_regs *regs = task_pt_regs(child); /* * psw and gprs are stored on the stack */ @@ -353,7 +374,11 @@ static int __poke_user(struct task_struct *child, addr_t addr, addr_t data) /* Invalid addressing mode bits */ return -EINVAL; } - *(addr_t *)((addr_t) &task_pt_regs(child)->psw + addr) = data; + + if (test_pt_regs_flag(regs, PIF_SYSCALL) && + addr == offsetof(struct user, regs.gprs[2])) + fixup_int_code(child, data); + *(addr_t *)((addr_t) ®s->psw + addr) = data; } else if (addr < (addr_t) (&dummy->regs.orig_gpr2)) { /* @@ -719,6 +744,10 @@ static int __poke_user_compat(struct task_struct *child, regs->psw.mask = (regs->psw.mask & ~PSW_MASK_BA) | (__u64)(tmp & PSW32_ADDR_AMODE); } else { + + if (test_pt_regs_flag(regs, PIF_SYSCALL) && + addr == offsetof(struct compat_user, regs.gprs[2])) + fixup_int_code(child, data); /* gpr 0-15 */ *(__u32*)((addr_t) ®s->psw + addr*2 + 4) = tmp; } -- 2.25.1