From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 43274 invoked by alias); 5 Nov 2019 17:57:33 -0000 Mailing-List: contact glibc-cvs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Archive: List-Post: List-Help: , Sender: glibc-cvs-owner@sourceware.org List-Subscribe: Received: (qmail 43215 invoked by uid 9943); 5 Nov 2019 17:57:33 -0000 Date: Tue, 05 Nov 2019 17:57:00 -0000 Message-ID: <20191105175733.43212.qmail@sourceware.org> Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit From: Adhemerval Zanella To: glibc-cvs@sourceware.org Subject: [glibc/release/2.29/master] mips: Force RWX stack for hard-float builds that can run on pre-4.8 kernels X-Act-Checkin: glibc X-Git-Author: Dragan Mladjenovic X-Git-Refname: refs/heads/release/2.29/master X-Git-Oldrev: 52a6381659ecf725efaf8972a94ce40ab9956e4e X-Git-Newrev: a7646651f83646c646f0d9172f1ba9f2dc95a5fc X-SW-Source: 2019-q4/txt/msg00280.txt.bz2 https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=a7646651f83646c646f0d9172f1ba9f2dc95a5fc commit a7646651f83646c646f0d9172f1ba9f2dc95a5fc Author: Dragan Mladjenovic Date: Fri Aug 23 16:38:04 2019 +0000 mips: Force RWX stack for hard-float builds that can run on pre-4.8 kernels Linux/Mips kernels prior to 4.8 could potentially crash the user process when doing FPU emulation while running on non-executable user stack. Currently, gcc doesn't emit .note.GNU-stack for mips, but that will change in the future. To ensure that glibc can be used with such future gcc, without silently resulting in binaries that might crash in runtime, this patch forces RWX stack for all built objects if configured to run against minimum kernel version less than 4.8. * sysdeps/unix/sysv/linux/mips/Makefile (test-xfail-check-execstack): Move under mips-has-gnustack != yes. (CFLAGS-.o*, ASFLAGS-.o*): New rules. Apply -Wa,-execstack if mips-force-execstack == yes. * sysdeps/unix/sysv/linux/mips/configure: Regenerated. * sysdeps/unix/sysv/linux/mips/configure.ac (mips-force-execstack): New var. Set to yes for hard-float builds with minimum_kernel < 4.8.0 or minimum_kernel not set at all. (mips-has-gnustack): New var. Use value of libc_cv_as_noexecstack if mips-force-execstack != yes, otherwise set to no. (cherry picked from commit 33bc9efd91de1b14354291fc8ebd5bce96379f12) Diff: --- sysdeps/unix/sysv/linux/mips/Makefile | 21 ++++++++++++---- sysdeps/unix/sysv/linux/mips/configure | 41 +++++++++++++++++++++++++++++++ sysdeps/unix/sysv/linux/mips/configure.ac | 32 ++++++++++++++++++++++++ 3 files changed, 89 insertions(+), 5 deletions(-) diff --git a/sysdeps/unix/sysv/linux/mips/Makefile b/sysdeps/unix/sysv/linux/mips/Makefile index 8217f42..03044e7 100644 --- a/sysdeps/unix/sysv/linux/mips/Makefile +++ b/sysdeps/unix/sysv/linux/mips/Makefile @@ -63,14 +63,25 @@ sysdep-dl-routines += dl-static sysdep_routines += dl-vdso endif - -# Supporting non-executable stacks on MIPS requires changes to both -# the Linux kernel and glibc. See -# and -# . +# If the compiler doesn't use GNU.stack note, +# this test is expected to fail. +ifneq ($(mips-has-gnustack),yes) test-xfail-check-execstack = yes endif +endif ifeq ($(subdir),stdlib) gen-as-const-headers += ucontext_i.sym endif + +ifeq ($(mips-force-execstack),yes) +CFLAGS-.o += -Wa,-execstack +CFLAGS-.os += -Wa,-execstack +CFLAGS-.op += -Wa,-execstack +CFLAGS-.oS += -Wa,-execstack + +ASFLAGS-.o += -Wa,-execstack +ASFLAGS-.os += -Wa,-execstack +ASFLAGS-.op += -Wa,-execstack +ASFLAGS-.oS += -Wa,-execstack +endif diff --git a/sysdeps/unix/sysv/linux/mips/configure b/sysdeps/unix/sysv/linux/mips/configure index 1ee7f41..25f98e0 100644 --- a/sysdeps/unix/sysv/linux/mips/configure +++ b/sysdeps/unix/sysv/linux/mips/configure @@ -475,3 +475,44 @@ if test -z "$arch_minimum_kernel"; then arch_minimum_kernel=4.5.0 fi fi + +# Check if we are supposed to run on kernels older than 4.8.0. If so, +# force executable stack to avoid potential runtime problems with fpu +# emulation. +# NOTE: The check below assumes that in absence of user-provided minumum_kernel +# we will default to arch_minimum_kernel which is currently less than 4.8.0 for +# all known configurations. If this changes, the check must be updated. +{ $as_echo "$as_me:${as_lineno-$LINENO}: checking whether the compiler must use executable stack" >&5 +$as_echo_n "checking whether the compiler must use executable stack... " >&6; } +if ${libc_cv_mips_force_execstack+:} false; then : + $as_echo_n "(cached) " >&6 +else + libc_cv_mips_force_execstack=no + if test $libc_mips_float = hard; then + if test -n "$minimum_kernel"; then + + min_version=$((`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1 \* 65536 + \2 \* 256 + \3/'`)) + + if test $min_version -lt 264192; then + libc_cv_mips_force_execstack=yes + fi + else + libc_cv_mips_force_execstack=yes + fi + fi +fi +{ $as_echo "$as_me:${as_lineno-$LINENO}: result: $libc_cv_mips_force_execstack" >&5 +$as_echo "$libc_cv_mips_force_execstack" >&6; } + +libc_mips_has_gnustack=$libc_cv_as_noexecstack + +if test $libc_cv_mips_force_execstack = yes; then + libc_mips_has_gnustack=no + { $as_echo "$as_me:${as_lineno-$LINENO}: WARNING: forcing executable stack for pre-4.8.0 Linux kernels" >&5 +$as_echo "$as_me: WARNING: forcing executable stack for pre-4.8.0 Linux kernels" >&2;} +fi + +config_vars="$config_vars +mips-force-execstack = ${libc_cv_mips_force_execstack}" +config_vars="$config_vars +mips-has-gnustack = ${libc_mips_has_gnustack}" diff --git a/sysdeps/unix/sysv/linux/mips/configure.ac b/sysdeps/unix/sysv/linux/mips/configure.ac index 9147aa4..3db1b32 100644 --- a/sysdeps/unix/sysv/linux/mips/configure.ac +++ b/sysdeps/unix/sysv/linux/mips/configure.ac @@ -134,3 +134,35 @@ if test -z "$arch_minimum_kernel"; then arch_minimum_kernel=4.5.0 fi fi + +# Check if we are supposed to run on kernels older than 4.8.0. If so, +# force executable stack to avoid potential runtime problems with fpu +# emulation. +# NOTE: The check below assumes that in absence of user-provided minumum_kernel +# we will default to arch_minimum_kernel which is currently less than 4.8.0 for +# all known configurations. If this changes, the check must be updated. +AC_CACHE_CHECK([whether the compiler must use executable stack], + libc_cv_mips_force_execstack, [dnl +libc_cv_mips_force_execstack=no + if test $libc_mips_float = hard; then + if test -n "$minimum_kernel"; then + changequote(,) + min_version=$((`echo "$minimum_kernel.0.0.0" | sed 's/\([0-9]*\)\.\([0-9]*\)\.\([0-9]*\).*/\1 \* 65536 + \2 \* 256 + \3/'`)) + changequote([,]) + if test $min_version -lt 264192; then + libc_cv_mips_force_execstack=yes + fi + else + libc_cv_mips_force_execstack=yes + fi + fi]) + +libc_mips_has_gnustack=$libc_cv_as_noexecstack + +if test $libc_cv_mips_force_execstack = yes; then + libc_mips_has_gnustack=no + AC_MSG_WARN([forcing executable stack for pre-4.8.0 Linux kernels]) +fi + +LIBC_CONFIG_VAR([mips-force-execstack],[${libc_cv_mips_force_execstack}]) +LIBC_CONFIG_VAR([mips-has-gnustack],[${libc_mips_has_gnustack}])