[PATCH 22/24] ARM64:ILP32: Fix signal return for ILP32 when the user modified the signal stack

[Andrew Pinski]

If the user decided to change the stack_t that was on the stack when returning
from the signal handler, the stack_t's padding for ILP32 might be not zero.
So we need to use the syscall version of restore_altstack (ilp32_sys_sigaltstack).

Signed-off-by: Andrew Pinski <apinski at cavium.com>
---
 arch/arm64/kernel/signal.c |   14 ++++++++++++++
 1 files changed, 14 insertions(+), 0 deletions(-)

diff --git a/arch/arm64/kernel/signal.c b/arch/arm64/kernel/signal.c
index 5311147..6316d54 100644
--- a/arch/arm64/kernel/signal.c
+++ b/arch/arm64/kernel/signal.c
@@ -35,6 +35,7 @@
 #include <asm/fpsimd.h>
 #include <asm/signal32.h>
 #include <asm/vdso.h>
+#include <asm/syscalls.h>
 
 /*
  * Do a signal return; undo the signal stack. These are aligned to 128-bit.
@@ -149,6 +150,19 @@ asmlinkage long sys_rt_sigreturn(struct pt_regs *regs)
 	if (restore_sigframe(regs, frame))
 		goto badframe;
 
+#ifdef CONFIG_ARM64_ILP32
+	/*
+	 * ILP32 has to be handled "special" due to maybe not zeroing out
+	 * the upper 32bits of the pointer if the user changed the frame.
+	 */
+	if (is_ilp32_compat_task()) {
+		if (ilp32_sys_sigaltstack(&frame->uc.uc_stack,
+					  NULL) == -EFAULT)
+			goto badframe;
+		return regs->regs[0];
+	}
+#endif
+
 	if (restore_altstack(&frame->uc.uc_stack))
 		goto badframe;
 
-- 
1.7.2.5