From: Helge Deller Date: Thu, 4 Jul 2019 01:44:17 +0000 (+0200) Subject: parisc: Ensure userspace privilege for ptraced processes in regset functions X-Git-Tag: v4.19.61~19 X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=a6a0daa775e84d72e292ffd0edb2fa9f246212e5;p=platform%2Fkernel%2Flinux-rpi.git parisc: Ensure userspace privilege for ptraced processes in regset functions commit 34c32fc603311a72cb558e5e337555434f64c27b upstream. On parisc the privilege level of a process is stored in the lowest two bits of the instruction pointers (IAOQ0 and IAOQ1). On Linux we use privilege level 0 for the kernel and privilege level 3 for user-space. So userspace should not be allowed to modify IAOQ0 or IAOQ1 of a ptraced process to change it's privilege level to e.g. 0 to try to gain kernel privileges. This patch prevents such modifications in the regset support functions by always setting the two lowest bits to one (which relates to privilege level 3 for user-space) if IAOQ0 or IAOQ1 are modified via ptrace regset calls. Link: https://bugs.gentoo.org/481768 Cc: # v4.7+ Tested-by: Rolf Eike Beer Signed-off-by: Helge Deller Signed-off-by: Greg Kroah-Hartman --- diff --git a/arch/parisc/kernel/ptrace.c b/arch/parisc/kernel/ptrace.c index 0964c23..855ccbca 100644 --- a/arch/parisc/kernel/ptrace.c +++ b/arch/parisc/kernel/ptrace.c @@ -496,7 +496,8 @@ static void set_reg(struct pt_regs *regs, int num, unsigned long val) return; case RI(iaoq[0]): case RI(iaoq[1]): - regs->iaoq[num - RI(iaoq[0])] = val; + /* set 2 lowest bits to ensure userspace privilege: */ + regs->iaoq[num - RI(iaoq[0])] = val | 3; return; case RI(sar): regs->sar = val; return;