From 8f66fce0f46560b9e910787ff7ad0974441c4f9c Mon Sep 17 00:00:00 2001 From: John David Anglin Date: Tue, 21 Dec 2021 13:21:22 -0500 Subject: parisc: Correct completer in lws start The completer in the "or,ev %r1,%r30,%r30" instruction is reversed, so we are not clipping the LWS number when we are called from a 32-bit process (W=0). We need to nulify the following depdi instruction when the least-significant bit of %r30 is 1. If the %r20 register is not clipped, a user process could perform a LWS call that would branch to an undefined location in the kernel and potentially crash the machine. Signed-off-by: John David Anglin Cc: stable@vger.kernel.org # 4.19+ Signed-off-by: Helge Deller --- arch/parisc/kernel/syscall.S | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'arch') diff --git a/arch/parisc/kernel/syscall.S b/arch/parisc/kernel/syscall.S index d2497b339d13..65c88ca7a7ac 100644 --- a/arch/parisc/kernel/syscall.S +++ b/arch/parisc/kernel/syscall.S @@ -472,7 +472,7 @@ lws_start: extrd,u %r1,PSW_W_BIT,1,%r1 /* sp must be aligned on 4, so deposit the W bit setting into * the bottom of sp temporarily */ - or,ev %r1,%r30,%r30 + or,od %r1,%r30,%r30 /* Clip LWS number to a 32-bit value for 32-bit processes */ depdi 0, 31, 32, %r20 -- cgit