From: Diana Craciun <diana.crac...@nxp.com>
commit c28218d4abbf4f2035495334d8bfcba64bda4787 upstream.
Used barrier_nospec to sanitize the syscall table.
Signed-off-by: Diana Craciun <diana.crac...@nxp.com>
Signed-off-by: Michael Ellerman <m...@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 4ae464b9d490..a2999cd73a82 100644
--- a/arch/powerpc/kernel/entry_32.S
+++ b/arch/powerpc/kernel/entry_32.S
@@ -33,6 +33,7 @@
#include <asm/unistd.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.
@@ -358,6 +359,15 @@ _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
