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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 0C9F5CDB47E for ; Sun, 15 Oct 2023 18:28:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229559AbjJOS2S (ORCPT ); Sun, 15 Oct 2023 14:28:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43180 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbjJOS2R (ORCPT ); Sun, 15 Oct 2023 14:28:17 -0400 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B0452B7 for ; Sun, 15 Oct 2023 11:28:15 -0700 (PDT) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 00459C433C8; Sun, 15 Oct 2023 18:28:14 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1697394495; bh=Bt0OUBB+jy9EIDwyOspj766yn8boBa/3v7UaKUwtkPc=; h=Subject:To:Cc:From:Date:From; b=OoUQ8lQSO0lFmQLRbj81xUj7KMJvmykGJYMCZBpPfQLXsZT5CV9RXe5tbEHARkpLa Q/bW70NDKH/QnOdL7nwbO5t9pJk8uCjT6g29w45mAxAFwHvXrQYaBTTrKAvvNwlbGe l51Zuh/nwieCHPs/mCx6LzlhJ0skqoDaEOAuZgk4= Subject: FAILED: patch "[PATCH] riscv: Only consider swbp/ss handlers for correct privileged" failed to apply to 5.15-stable tree To: bjorn@rivosinc.com, guoren@kernel.org, namcaov@gmail.com, palmer@rivosinc.com, puranjay12@gmail.com Cc: From: Date: Sun, 15 Oct 2023 20:28:03 +0200 Message-ID: <2023101503-astride-vacant-a511@gregkh> 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 The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-5.15.y git checkout FETCH_HEAD git cherry-pick -x 9f564b92cf6d0ecb398f9348600a7d8a7f8ea804 # git commit -s git send-email --to '' --in-reply-to '2023101503-astride-vacant-a511@gregkh' --subject-prefix 'PATCH 5.15.y' HEAD^.. Possible dependencies: 9f564b92cf6d ("riscv: Only consider swbp/ss handlers for correct privileged mode") f0bddf50586d ("riscv: entry: Convert to generic entry") c3ec1e8964fb ("Merge patch series "RISC-V: Align the shadow stack"") thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 9f564b92cf6d0ecb398f9348600a7d8a7f8ea804 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Bj=C3=B6rn=20T=C3=B6pel?= Date: Tue, 12 Sep 2023 08:56:19 +0200 Subject: [PATCH] riscv: Only consider swbp/ss handlers for correct privileged mode MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit RISC-V software breakpoint trap handlers are used for {k,u}probes. When trapping from kernelmode, only the kernelmode handlers should be considered. Vice versa, only usermode handlers for usermode traps. This is not the case on RISC-V, which can trigger a bug if a userspace process uses uprobes, and a WARN() is triggered from kernelmode (which is implemented via {c.,}ebreak). The kernel will trap on the kernelmode {c.,}ebreak, look for uprobes handlers, realize incorrectly that uprobes need to be handled, and exit the trap handler early. The trap returns to re-executing the {c.,}ebreak, and enter an infinite trap-loop. The issue was found running the BPF selftest [1]. Fix this issue by only considering the swbp/ss handlers for kernel/usermode respectively. Also, move CONFIG ifdeffery from traps.c to the asm/{k,u}probes.h headers. Note that linux/uprobes.h only include asm/uprobes.h if CONFIG_UPROBES is defined, which is why asm/uprobes.h needs to be unconditionally included in traps.c Link: https://lore.kernel.org/linux-riscv/87v8d19aun.fsf@all.your.base.are.belong.to.us/ # [1] Fixes: 74784081aac8 ("riscv: Add uprobes supported") Reviewed-by: Guo Ren Reviewed-by: Nam Cao Tested-by: Puranjay Mohan Signed-off-by: Björn Töpel Link: https://lore.kernel.org/r/20230912065619.62020-1-bjorn@kernel.org Signed-off-by: Palmer Dabbelt diff --git a/arch/riscv/include/asm/kprobes.h b/arch/riscv/include/asm/kprobes.h index e7882ccb0fd4..78ea44f76718 100644 --- a/arch/riscv/include/asm/kprobes.h +++ b/arch/riscv/include/asm/kprobes.h @@ -40,6 +40,15 @@ void arch_remove_kprobe(struct kprobe *p); int kprobe_fault_handler(struct pt_regs *regs, unsigned int trapnr); bool kprobe_breakpoint_handler(struct pt_regs *regs); bool kprobe_single_step_handler(struct pt_regs *regs); - +#else +static inline bool kprobe_breakpoint_handler(struct pt_regs *regs) +{ + return false; +} + +static inline bool kprobe_single_step_handler(struct pt_regs *regs) +{ + return false; +} #endif /* CONFIG_KPROBES */ #endif /* _ASM_RISCV_KPROBES_H */ diff --git a/arch/riscv/include/asm/uprobes.h b/arch/riscv/include/asm/uprobes.h index f2183e00fdd2..3fc7deda9190 100644 --- a/arch/riscv/include/asm/uprobes.h +++ b/arch/riscv/include/asm/uprobes.h @@ -34,7 +34,18 @@ struct arch_uprobe { bool simulate; }; +#ifdef CONFIG_UPROBES bool uprobe_breakpoint_handler(struct pt_regs *regs); bool uprobe_single_step_handler(struct pt_regs *regs); - +#else +static inline bool uprobe_breakpoint_handler(struct pt_regs *regs) +{ + return false; +} + +static inline bool uprobe_single_step_handler(struct pt_regs *regs) +{ + return false; +} +#endif /* CONFIG_UPROBES */ #endif /* _ASM_RISCV_UPROBES_H */ diff --git a/arch/riscv/kernel/traps.c b/arch/riscv/kernel/traps.c index 19807c4d3805..fae8f610d867 100644 --- a/arch/riscv/kernel/traps.c +++ b/arch/riscv/kernel/traps.c @@ -13,6 +13,8 @@ #include #include #include +#include +#include #include #include #include @@ -247,22 +249,28 @@ static inline unsigned long get_break_insn_length(unsigned long pc) return GET_INSN_LENGTH(insn); } +static bool probe_single_step_handler(struct pt_regs *regs) +{ + bool user = user_mode(regs); + + return user ? uprobe_single_step_handler(regs) : kprobe_single_step_handler(regs); +} + +static bool probe_breakpoint_handler(struct pt_regs *regs) +{ + bool user = user_mode(regs); + + return user ? uprobe_breakpoint_handler(regs) : kprobe_breakpoint_handler(regs); +} + void handle_break(struct pt_regs *regs) { -#ifdef CONFIG_KPROBES - if (kprobe_single_step_handler(regs)) + if (probe_single_step_handler(regs)) return; - if (kprobe_breakpoint_handler(regs)) - return; -#endif -#ifdef CONFIG_UPROBES - if (uprobe_single_step_handler(regs)) + if (probe_breakpoint_handler(regs)) return; - if (uprobe_breakpoint_handler(regs)) - return; -#endif current->thread.bad_cause = regs->cause; if (user_mode(regs))