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Message-Id: <20190724191749.824479528@linuxfoundation.org>
Date: Wed, 24 Jul 2019 21:21:39 +0200
From: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To: linux-kernel@...r.kernel.org
Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
stable@...r.kernel.org, Rolf Eike Beer <eike-kernel@...tec.de>,
Helge Deller <deller@....de>
Subject: [PATCH 5.1 347/371] parisc: Ensure userspace privilege for ptraced processes in regset functions
From: Helge Deller <deller@....de>
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: <stable@...r.kernel.org> # v4.7+
Tested-by: Rolf Eike Beer <eike-kernel@...tec.de>
Signed-off-by: Helge Deller <deller@....de>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
arch/parisc/kernel/ptrace.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/parisc/kernel/ptrace.c
+++ b/arch/parisc/kernel/ptrace.c
@@ -496,7 +496,8 @@ static void set_reg(struct pt_regs *regs
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;
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