Do not stack-protect ifunc resolvers [BZ #7065]

When dynamically linking, ifunc resolvers are called before TLS is
initialized, so they cannot be safely stack-protected.

We avoid disabling stack-protection on large numbers of files by
using __attribute__ ((__optimize__ ("-fno-stack-protector")))
to turn it off just for the resolvers themselves.  (We provide
the attribute even when statically linking, because we will later
use it elsewhere too.)

6 files changed, 8 insertions, 0 deletions

diff --git a/sysdeps/generic/ifunc-sel.h b/sysdeps/generic/ifunc-sel.h
index 6a27b69..1fff405 100644
--- a/sysdeps/generic/ifunc-sel.h
+++ b/sysdeps/generic/ifunc-sel.h
@@ -5,6 +5,7 @@
 extern int global;
 
 static inline void *
+inhibit_stack_protector
 ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
 {
  switch (global)
@@ -19,6 +20,7 @@ ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
 }
 
 static inline void *
+inhibit_stack_protector
 ifunc_one (int (*f1) (void))
 {
   return f1;
diff --git a/sysdeps/nacl/nacl_interface_query.c b/sysdeps/nacl/nacl_interface_query.c
index adf1dd4..dbaa88b 100644
--- a/sysdeps/nacl/nacl_interface_query.c
+++ b/sysdeps/nacl/nacl_interface_query.c
@@ -29,6 +29,7 @@ extern TYPE_nacl_irt_query nacl_interface_query_ifunc (void)
   asm ("nacl_interface_query");
 
 TYPE_nacl_irt_query
+inhibit_stack_protector
 nacl_interface_query_ifunc (void)
 {
   return &__nacl_irt_query;
diff --git a/sysdeps/powerpc/ifunc-sel.h b/sysdeps/powerpc/ifunc-sel.h
index ac589bd..bdb00bf 100644
--- a/sysdeps/powerpc/ifunc-sel.h
+++ b/sysdeps/powerpc/ifunc-sel.h
@@ -5,6 +5,7 @@
 extern int global;
 
 static inline void *
+inhibit_stack_protector
 ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
 {
   register void *ret __asm__ ("r3");
@@ -32,6 +33,7 @@ ifunc_sel (int (*f1) (void), int (*f2) (void), int (*f3) (void))
 }
 
 static inline void *
+inhibit_stack_protector
 ifunc_one (int (*f1) (void))
 {
   register void *ret __asm__ ("r3");
diff --git a/sysdeps/unix/make-syscalls.sh b/sysdeps/unix/make-syscalls.sh
index 58d165e..123553c 100644
--- a/sysdeps/unix/make-syscalls.sh
+++ b/sysdeps/unix/make-syscalls.sh
@@ -287,6 +287,7 @@ while read file srcfile caller syscall args strong weak; do
 	(echo '#include <dl-vdso.h>'; \\
 	 echo 'extern void *${strong}_ifunc (void) __asm ("${strong}");'; \\
 	 echo 'void *'; \\
+	 echo 'inhibit_stack_protector'; \\
 	 echo '${strong}_ifunc (void)'; \\
 	 echo '{'; \\
 	 echo '  PREPARE_VERSION_KNOWN (symver, ${vdso_symver});'; \\
diff --git a/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c b/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
index cbac4b3..8436f9d 100644
--- a/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
+++ b/sysdeps/unix/sysv/linux/x86_64/x32/getcpu.c
@@ -21,6 +21,7 @@
 void *getcpu_ifunc (void) __asm__ ("__getcpu");
 
 void *
+inhibit_stack_protector
 getcpu_ifunc (void)
 {
   PREPARE_VERSION (linux26, "LINUX_2.6", 61765110);
diff --git a/sysdeps/x86_64/ifuncmod8.c b/sysdeps/x86_64/ifuncmod8.c
index c004367..7c06562 100644
--- a/sysdeps/x86_64/ifuncmod8.c
+++ b/sysdeps/x86_64/ifuncmod8.c
@@ -28,6 +28,7 @@ foo_impl (float x)
 }
 
 void *
+inhibit_stack_protector
 foo_ifunc (void)
 {
   __m128i xmm = _mm_set1_epi32 (-1);