diff mbox

[12/15] Do not stack-protect sigreturn stubs.

Message ID 20161219111528.14969-13-nix@esperi.org.uk
State Committed
Headers

Commit Message

Nix Dec. 19, 2016, 11:15 a.m. UTC 
  From: Nick Alcock <nick.alcock@oracle.com>

These are called from the kernel with the stack at a carefully-
chosen location so that the stack frame can be restored: they must not
move the stack pointer lest garbage be restored into the registers.

We explicitly inhibit protection for SPARC and for signal/sigreturn.c:
other arches either define their sigreturn stubs in .S files, or (i386,
x86_64, mips) use macros expanding to top-level asm blocks and explicit
labels in the text section to mock up a "function" without telling the
compiler that one is there at all.

v2: New.
v3: Use $(no-stack-protector).
v4: Use inhibit_stack_protector.
v7: Add sigreturn.c.

	* signal/Makefile (CFLAGS-sigreturn.c): Use
	$(no-stack-protector).
	* sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c:
	(__rt_sigreturn_stub): Use inhibit_stack_protector.
	* sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c
	(__rt_sigreturn_stub): Likewise.
	(__sigreturn_stub): Likewise.
---
 signal/Makefile                                   | 2 ++
 sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c | 8 ++++++--
 sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c | 4 +++-
 3 files changed, 11 insertions(+), 3 deletions(-)
diff mbox

Patch

diff --git a/signal/Makefile b/signal/Makefile
index 9d29ff4..ccd6f51 100644
--- a/signal/Makefile
+++ b/signal/Makefile
@@ -48,3 +48,5 @@  CFLAGS-sigsuspend.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-sigtimedwait.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-sigwait.c = -fexceptions -fasynchronous-unwind-tables
 CFLAGS-sigwaitinfo.c = -fexceptions -fasynchronous-unwind-tables
+
+CFLAGS-sigreturn.c = $(no-stack-protector)
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c b/sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c
index 5aa3c35..b75142f 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c
+++ b/sysdeps/unix/sysv/linux/sparc/sparc32/sigaction.c
@@ -65,7 +65,9 @@  libc_hidden_def (__libc_sigaction)
 #include <nptl/sigaction.c>
 
 
-static void
+static
+inhibit_stack_protector
+void
 __rt_sigreturn_stub (void)
 {
   __asm__ ("mov %0, %%g1\n\t"
@@ -74,7 +76,9 @@  __rt_sigreturn_stub (void)
 	   : "i" (__NR_rt_sigreturn));
 }
 
-static void
+static
+inhibit_stack_protector
+void
 __sigreturn_stub (void)
 {
   __asm__ ("mov %0, %%g1\n\t"
diff --git a/sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c b/sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c
index 50c444c..058c011 100644
--- a/sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c
+++ b/sysdeps/unix/sysv/linux/sparc/sparc64/sigaction.c
@@ -66,7 +66,9 @@  libc_hidden_def (__libc_sigaction)
 #include <nptl/sigaction.c>
 
 
-static void
+static
+inhibit_stack_protector
+void
 __rt_sigreturn_stub (void)
 {
   __asm__ ("mov %0, %%g1\n\t"