[PATCH stable v4.9 17/35] powerpc/fsl: Sanitize the syscall table for NXP PowerPC 32 bit platforms

Michael Ellerman
2019-04-11T11:47:02Z

From: Diana Craciun <diana.craciun@nxp.com>

commit c28218d4abbf4f2035495334d8bfcba64bda4787 upstream.

Used barrier_nospec to sanitize the syscall table.

Signed-off-by: Diana Craciun <diana.craciun@nxp.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
---
arch/powerpc/kernel/entry_32.S | 10 ++++++++++
1 file changed, 10 insertions(+)

diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S
index 370645687cc7..bdd88f9d7926 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -34,6 +34,7 @@
#include <asm/ftrace.h>
#include <asm/ptrace.h>
#include <asm/export.h>
+#include <asm/barrier.h>

/*
* MSR_KERNEL is > 0x10000 on 4xx/Book-E since it include MSR_CE.
@@ -347,6 +348,15 @@ _GLOBAL(DoSyscall)
ori r10,r10,sys_call_table@l
slwi r0,r0,2
bge- 66f
+
+ barrier_nospec_asm
+ /*
+ * Prevent the load of the handler below (based on the user-passed
+ * system call number) being speculatively executed until the test
+ * against NR_syscalls and branch to .66f above has
+ * committed.
+ */
+
lwzx r10,r10,r0 /* Fetch system call handler [ptr] */
mtlr r10
addi r9,r1,STACK_FRAME_OVERHEAD
--
2.20.1