[PATCH] s390/signal: Fix incorrect return address in signal frame

[Heiko Carstens <hca@linux.ibm.com>]

exit_to_user_mode_loop() can call arch_do_signal_or_restart() multiple
times when signals are pending.

If the first call set up a vDSO system call restart by saving the real
user return address and adjusting psw.addr so it points to the vDSO stub,
a second call builds the signal frame with the wrong return address.

Restore psw.addr from arch_data before building the signal frame.

Fixes: df29a7440c4b ("s390/signal: switch to using vdso for sigreturn and syscall restart")
Cc: stable@vger.kernel.org
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
---
 arch/s390/kernel/signal.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/arch/s390/kernel/signal.c b/arch/s390/kernel/signal.c
index 4874de5edea0..25781d4a0ad0 100644
--- a/arch/s390/kernel/signal.c
+++ b/arch/s390/kernel/signal.c
@@ -475,7 +475,10 @@ void arch_do_signal_or_restart(struct pt_regs *regs)
 		}
 		/* No longer in a system call */
 		clear_pt_regs_flag(regs, PIF_SYSCALL);
-
+		if (!(current->restart_block.arch_data & 1)) {
+			regs->psw.addr = current->restart_block.arch_data;
+			current->restart_block.arch_data = 1;
+		}
 		rseq_signal_deliver(&ksig, regs);
 		handle_signal(&ksig, oldset, regs);
 		return;
-- 
2.53.0