From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AH8x226qhVIGL+nPSfW5+qwTmRLqnphvWfKcOMm0M0TupWIjit7XhwOPSFZpK8DzH+0GXMKLvjzT ARC-Seal: i=1; a=rsa-sha256; t=1517855140; cv=none; d=google.com; s=arc-20160816; b=z7GYKjM57pEeuo+61P8YCHAMPJFbXaMXLnuxUYFe5wpzqZ8pucXpcpPFCCZARuxbuz gAPi4dsJjYtTDxQ/C/GhypoLC6fr34qGR7DEzgNdwom5v6i6106liKraLT6zY10iWTRg tF4gEMo/obRrMrPJuaila/0v8aWwAbW0/mk+SCljYIh5o7vu6f7IS/JCK9aHMvf2nb+N 3FeKvTtXtiUPorG0UwLRCcHNQC9jNHuXiC/U5hLQJqJ9JIOZSQdGsNG++P451OctNrw3 J8vLlXE8KSXB/469+lL020adllyElONH0fbyicsVz2oN0HdStsM+TfJKMOyWLQMsewRN hgrA== 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=RQeE7capP/jrjJMaLqf/QwkBdWS9xA5WfMUeJPjv+qU=; b=WeUicLDMHGrNn6IIZNG8lRgbcY28j29LdUwMxumN7zNN7FjlytXIeOBevJWWI8Uh/m k6ufY0bvTlgV4Kzx12QvnSCHiIBMJ5bhFYIhJHo4svLc/z6GXN8RqKqrK5rm4VspxJEf WmCUofUwf2D5P5mxvfxfpLD73eBLNqWZiJbJ7EyNHJ7fQfLn7eB/Ck7CFLLhQdIQDc3J teLdzYmQh/iS8qnw2u+95bBO7lmdPMNR/FHdn5teRkZCKwj1fGGBIeXqwYypOCGj7y91 aDd05tHqkhflTJBuSh7L4aCllsdNcSGsZgMq/ngAT0fMF4dtoNIOPPNy41rtJVOnnGSg 56Hw== ARC-Authentication-Results: i=1; mx.google.com; spf=softfail (google.com: domain of transitioning gregkh@linuxfoundation.org does not designate 104.132.1.108 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 104.132.1.108 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, Linus Torvalds , Dan Williams , Thomas Gleixner , linux-arch@vger.kernel.org, kernel-hardening@lists.openwall.com, Andy Lutomirski , alan@linux.intel.com Subject: [PATCH 4.15 40/60] x86/syscall: Sanitize syscall table de-references under speculation Date: Mon, 5 Feb 2018 10:23:13 -0800 Message-Id: <20180205182215.617155182@linuxfoundation.org> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180205182213.902626065@linuxfoundation.org> References: <20180205182213.902626065@linuxfoundation.org> User-Agent: quilt/0.65 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?1591586416249692382?= X-GMAIL-MSGID: =?utf-8?q?1591586472160165292?= 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 dan.j.williams@intel.com commit 2fbd7af5af8665d18bcefae3e9700be07e22b681 The syscall table base is a user controlled function pointer in kernel space. Use array_index_nospec() to prevent any out of bounds speculation. While retpoline prevents speculating into a userspace directed target it does not stop the pointer de-reference, the concern is leaking memory relative to the syscall table base, by observing instruction cache behavior. Reported-by: Linus Torvalds Signed-off-by: Dan Williams Signed-off-by: Thomas Gleixner Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Andy Lutomirski Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727417984.33451.1216731042505722161.stgit@dwillia2-desk3.amr.corp.intel.com Signed-off-by: Greg Kroah-Hartman --- arch/x86/entry/common.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) --- a/arch/x86/entry/common.c +++ b/arch/x86/entry/common.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include #include @@ -282,7 +283,8 @@ __visible void do_syscall_64(struct pt_r * regs->orig_ax, which changes the behavior of some syscalls. */ if (likely((nr & __SYSCALL_MASK) < NR_syscalls)) { - regs->ax = sys_call_table[nr & __SYSCALL_MASK]( + nr = array_index_nospec(nr & __SYSCALL_MASK, NR_syscalls); + regs->ax = sys_call_table[nr]( regs->di, regs->si, regs->dx, regs->r10, regs->r8, regs->r9); } @@ -318,6 +320,7 @@ static __always_inline void do_syscall_3 } if (likely(nr < IA32_NR_syscalls)) { + nr = array_index_nospec(nr, IA32_NR_syscalls); /* * It's possible that a 32-bit syscall implementation * takes a 64-bit parameter but nonetheless assumes that