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

Andrew Pinski
2014-09-03T21:23:59Z

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@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