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[glibc/release/2.24/master] mips: Force RWX stack for hard-float builds that can run on pre-4.8 kernels
- From: Adhemerval Zanella <azanella at sourceware dot org>
- To: glibc-cvs at sourceware dot org
- Date: 5 Nov 2019 16:52:27 -0000
- Subject: [glibc/release/2.24/master] mips: Force RWX stack for hard-float builds that can run on pre-4.8 kernels
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=910576119f1876f7a522be826302c399c1f40ca7
commit 910576119f1876f7a522be826302c399c1f40ca7
Author: Dragan Mladjenovic <dmladjenovic@wavecomp.com>
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:
---
ChangeLog | 16 ++++++++++++
sysdeps/unix/sysv/linux/mips/Makefile | 17 +++++++++++++
sysdeps/unix/sysv/linux/mips/configure | 41 +++++++++++++++++++++++++++++++
sysdeps/unix/sysv/linux/mips/configure.ac | 32 ++++++++++++++++++++++++
4 files changed, 106 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index a911573..3ca1f72 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,19 @@
+2019-11-01 Dragan Mladjenovic <dmladjenovic@wavecomp.com>
+
+ * 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.
+
2019-02-04 H.J. Lu <hongjiu.lu@intel.com>
[BZ #24155]
diff --git a/sysdeps/unix/sysv/linux/mips/Makefile b/sysdeps/unix/sysv/linux/mips/Makefile
index c6729c1..a58e695 100644
--- a/sysdeps/unix/sysv/linux/mips/Makefile
+++ b/sysdeps/unix/sysv/linux/mips/Makefile
@@ -99,8 +99,25 @@ sysdep-dl-routines += dl-static
sysdep_routines += dl-vdso
endif
+# 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 ($(mips-force-execstack),yes)
+CFLAGS-.o += -Wa,-execstack
+CFLAGS-.os += -Wa,-execstack
+CFLAGS-.op += -Wa,-execstack
+CFLAGS-.oS += -Wa,-execstack
+
+ASFLAGS-.o += -Wa,-execstack
+ASFLAGS-.os += -Wa,-execstack
+ASFLAGS-.op += -Wa,-execstack
+ASFLAGS-.oS += -Wa,-execstack
+endif
diff --git a/sysdeps/unix/sysv/linux/mips/configure b/sysdeps/unix/sysv/linux/mips/configure
index a5513fa..2ec86a3 100644
--- a/sysdeps/unix/sysv/linux/mips/configure
+++ b/sysdeps/unix/sysv/linux/mips/configure
@@ -475,3 +475,44 @@ if test -z "$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}])