From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x227Sj8NDJZymcxd+vrBTMCiRwggwovcQfZg6VAEIqYbjmsns91w/20jI9sikDRBAjMHQGe6q ARC-Seal: i=1; a=rsa-sha256; t=1519218567; cv=none; d=google.com; s=arc-20160816; b=BLZ3Y6Q1qGTJqPllIwIfBi046ipv/Pzwl7RAhBwf5B+PaRcyqrjYZEfEiz8xS6sZoh EsRXhCJ1jeDTY4b4GEWFmnVrPh6yvK7X1t0L3yGhq2ZIVmhy7T/3w7pUr9sPd9Adn8vD 7wBJ+WvcNqj+5LzldWqJg57nQlH75xhzucm+jucXs/LWT3mn6msH300T/5FkKVRyG4Hv LMOcJPFwnn8tY6xC2IljOsKIzMF4fIUlGwsXM+hwPzjcLbhyvUL5p63sZ48DGCL+RX7o gYbD44Y/BOjk5T+aRHLwZugAr+SUBDAWjmFRPcQsAyeeRM8Caiea656Y9L2elH/q4LVk TPJQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:arc-authentication-results; bh=DbSwcU1EDgrYraAKeULX0sFIJMCXUBAD2MNMfJXpu70=; b=oVTM9nwYrZeAwUtmu9fdEt91V0kWIaqKW0LYMGGIrsmL794aVBTd9CYJ6RgcQxwxgw YQkq2tbAc95jhUogGwI8Bf1iI9Q/rMa29IOdLRHBvPSHcmeBTrmm4hPW0IiTYrn+fmy2 mKM3TLcc/mqGvnOEtAkbN5Jjk7AidrBCeG57c+QbIH3vT0MCj1+aV1nmJF7Cs+iWvnrk Y8GDU2zw6jDNHfRhqrcFoiQzHxtZvbHL5H7Ba48RrXDhrPh3tjhbHpkTY1a39U9YUWPm +7KQ3vbuV0BpJgKXXZ8Q/0QJUnpwVza754RbaRzq0M0Viv4C7gbB9Brl3YNAAHHMihdE 4Uvg== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org Authentication-Results: mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 90.92.71.90 as permitted sender) smtp.mailfrom=gregkh@linuxfoundation.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Dan Williams , Andy Lutomirski , Borislav Petkov , Brian Gerst , Denys Vlasenko , "H. Peter Anvin" , Josh Poimboeuf , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar Subject: [PATCH 4.15 058/163] x86/entry/64: Clear registers for exceptions/interrupts, to reduce speculation attack surface Date: Wed, 21 Feb 2018 13:48:07 +0100 Message-Id: <20180221124533.671163678@linuxfoundation.org> X-Mailer: git-send-email 2.16.2 In-Reply-To: <20180221124529.931834518@linuxfoundation.org> References: <20180221124529.931834518@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1593015548902748205?= X-GMAIL-MSGID: =?utf-8?q?1593016128947257780?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dan Williams commit 3ac6d8c787b835b997eb23e43e09aa0895ef7d58 upstream. Clear the 'extra' registers on entering the 64-bit kernel for exceptions and interrupts. The common registers are not cleared since they are likely clobbered well before they can be exploited in a speculative execution attack. Originally-From: Andi Kleen Signed-off-by: Dan Williams Cc: Cc: Andy Lutomirski Cc: Borislav Petkov Cc: Brian Gerst Cc: Denys Vlasenko Cc: H. Peter Anvin Cc: Josh Poimboeuf Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/151787989146.7847.15749181712358213254.stgit@dwillia2-desk3.amr.corp.intel.com [ Made small improvements to the changelog and the code comments. ] Signed-off-by: Ingo Molnar Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/calling.h | 19 +++++++++++++++++++ arch/x86/entry/entry_64.S | 6 +++++- 2 files changed, 24 insertions(+), 1 deletion(-) --- a/arch/x86/entry/calling.h +++ b/arch/x86/entry/calling.h @@ -147,6 +147,25 @@ For 32-bit we have the following convent UNWIND_HINT_REGS offset=\offset .endm + /* + * Sanitize registers of values that a speculation attack + * might otherwise want to exploit. The lower registers are + * likely clobbered well before they could be put to use in + * a speculative execution gadget: + */ + .macro CLEAR_REGS_NOSPEC + xorl %ebp, %ebp + xorl %ebx, %ebx + xorq %r8, %r8 + xorq %r9, %r9 + xorq %r10, %r10 + xorq %r11, %r11 + xorq %r12, %r12 + xorq %r13, %r13 + xorq %r14, %r14 + xorq %r15, %r15 + .endm + .macro POP_EXTRA_REGS popq %r15 popq %r14 --- a/arch/x86/entry/entry_64.S +++ b/arch/x86/entry/entry_64.S @@ -575,6 +575,7 @@ END(irq_entries_start) ALLOC_PT_GPREGS_ON_STACK SAVE_C_REGS SAVE_EXTRA_REGS + CLEAR_REGS_NOSPEC ENCODE_FRAME_POINTER testb $3, CS(%rsp) @@ -1133,6 +1134,7 @@ ENTRY(xen_failsafe_callback) ALLOC_PT_GPREGS_ON_STACK SAVE_C_REGS SAVE_EXTRA_REGS + CLEAR_REGS_NOSPEC ENCODE_FRAME_POINTER jmp error_exit END(xen_failsafe_callback) @@ -1178,6 +1180,7 @@ ENTRY(paranoid_entry) cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 + CLEAR_REGS_NOSPEC ENCODE_FRAME_POINTER 8 movl $1, %ebx movl $MSR_GS_BASE, %ecx @@ -1230,8 +1233,8 @@ ENTRY(error_entry) cld SAVE_C_REGS 8 SAVE_EXTRA_REGS 8 + CLEAR_REGS_NOSPEC ENCODE_FRAME_POINTER 8 - xorl %ebx, %ebx testb $3, CS+8(%rsp) jz .Lerror_kernelspace @@ -1428,6 +1431,7 @@ ENTRY(nmi) pushq %r14 /* pt_regs->r14 */ pushq %r15 /* pt_regs->r15 */ UNWIND_HINT_REGS + CLEAR_REGS_NOSPEC ENCODE_FRAME_POINTER /*