[PATCH] fix incorrect SA_ONSTACK behaviour for 64-bit processes

- When setting a sighandler using sigaction() call, if the flag
  SA_ONSTACK is set and no alternate stack is provided via sigaltstack(),
  the kernel still try to install the alternate stack.  This behavior is
  the opposite of the one which is documented in Single Unix Specifications
  V3.

- Also when setting an alternate stack using sigaltstack() with the flag
  SS_DISABLE, the kernel try to install the alternate stack on signal
  delivery.

These two use cases makes the process crash at signal delivery.

Signed-off-by: Laurent Meyer <meyerlau@fr.ibm.com>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Chris Zankel <chris@zankel.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/alpha/kernel/signal.c

@@ -375,7 +375,7 @@ do_rt_sigreturn(struct rt_sigframe __user *frame, struct pt_regs *regs,
 static inline void __user *
 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 {
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp + current->sas_ss_size;
 
 	return (void __user *)((sp - frame_size) & -32ul);

arch/frv/kernel/signal.c

@@ -233,7 +233,7 @@ static inline void __user *get_sigframe(struct k_sigaction *ka,
 
 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
-		if (! on_sig_stack(sp))
+		if (! sas_ss_flags(sp))
 			sp = current->sas_ss_sp + current->sas_ss_size;
 	}
 

arch/h8300/kernel/signal.c

@@ -307,7 +307,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 
 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
-		if (!on_sig_stack(usp))
+		if (!sas_ss_flags(usp))
 			usp = current->sas_ss_sp + current->sas_ss_size;
 	}
 	return (void *)((usp - frame_size) & -8UL);

arch/m68k/kernel/signal.c

@@ -763,7 +763,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 
 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
-		if (!on_sig_stack(usp))
+		if (!sas_ss_flags(usp))
 			usp = current->sas_ss_sp + current->sas_ss_size;
 	}
 	return (void __user *)((usp - frame_size) & -8UL);

arch/m68knommu/kernel/signal.c

@@ -553,7 +553,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 
 	/* This is the X/Open sanctioned signal stack switching.  */
 	if (ka->sa.sa_flags & SA_ONSTACK) {
-		if (!on_sig_stack(usp))
+		if (!sas_ss_flags(usp))
 			usp = current->sas_ss_sp + current->sas_ss_size;
 	}
 	return (void *)((usp - frame_size) & -8UL);

arch/parisc/kernel/signal.c

@@ -248,7 +248,7 @@ get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 	DBG(1,"get_sigframe: ka = %#lx, sp = %#lx, frame_size = %#lx\n",
 			(unsigned long)ka, sp, frame_size);
 
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp; /* Stacks grow up! */
 
 	DBG(1,"get_sigframe: Returning sp = %#lx\n", (unsigned long)sp);

arch/sh64/kernel/signal.c

@@ -407,7 +407,7 @@ setup_sigcontext(struct sigcontext __user *sc, struct pt_regs *regs,
 static inline void __user *
 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 {
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp + current->sas_ss_size;
 
 	return (void __user *)((sp - frame_size) & -8ul);

arch/v850/kernel/signal.c

@@ -274,7 +274,7 @@ get_sigframe(struct k_sigaction *ka, struct pt_regs *regs, size_t frame_size)
 	/* Default to using normal stack */
 	unsigned long sp = regs->gpr[GPR_SP];
 
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp + current->sas_ss_size;
 
 	return (void *)((sp - frame_size) & -8UL);

arch/xtensa/kernel/signal.c

@@ -433,7 +433,7 @@ asmlinkage int sys_rt_sigreturn(struct pt_regs *regs)
 static inline void *
 get_sigframe(struct k_sigaction *ka, unsigned long sp, size_t frame_size)
 {
-	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! on_sig_stack(sp))
+	if ((ka->sa.sa_flags & SA_ONSTACK) != 0 && ! sas_ss_flags(sp))
 		sp = current->sas_ss_sp + current->sas_ss_size;
 
 	return (void *)((sp - frame_size) & -16ul);