linux-kernel - [PATCH 3.16 308/366] MIPS: Fix ptrace(2) PTRACE_PEEKUSR and PTRACE

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Message-ID: <lsq.1539530741.166439063@decadent.org.uk>
Date:   Sun, 14 Oct 2018 16:25:41 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, "Maciej W. Rozycki" <macro@...s.com>,
        "Ralf Baechle" <ralf@...ux-mips.org>, linux-mips@...ux-mips.org,
        "James Hogan" <jhogan@...nel.org>
Subject: [PATCH 3.16 308/366] MIPS: Fix ptrace(2) PTRACE_PEEKUSR and
 PTRACE_POKEUSR accesses to o32 FGRs

3.16.60-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: "Maciej W. Rozycki" <macro@...s.com>

commit 9a3a92ccfe3620743d4ae57c987dc8e9c5f88996 upstream.

Check the TIF_32BIT_FPREGS task setting of the tracee rather than the
tracer in determining the layout of floating-point general registers in
the floating-point context, correcting access to odd-numbered registers
for o32 tracees where the setting disagrees between the two processes.

Fixes: 597ce1723e0f ("MIPS: Support for 64-bit FP with O32 binaries")
Signed-off-by: Maciej W. Rozycki <macro@...s.com>
Cc: Ralf Baechle <ralf@...ux-mips.org>
Cc: linux-mips@...ux-mips.org
Signed-off-by: James Hogan <jhogan@...nel.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 arch/mips/kernel/ptrace.c   | 4 ++--
 arch/mips/kernel/ptrace32.c | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)

--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -741,7 +741,7 @@ long arch_ptrace(struct task_struct *chi
 			fregs = get_fpu_regs(child);
 
 #ifdef CONFIG_32BIT
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even
@@ -830,7 +830,7 @@ long arch_ptrace(struct task_struct *chi
 
 			init_fp_ctx(child);
 #ifdef CONFIG_32BIT
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even
--- a/arch/mips/kernel/ptrace32.c
+++ b/arch/mips/kernel/ptrace32.c
@@ -97,7 +97,7 @@ long compat_arch_ptrace(struct task_stru
 				break;
 			}
 			fregs = get_fpu_regs(child);
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even
@@ -203,7 +203,7 @@ long compat_arch_ptrace(struct task_stru
 				       sizeof(child->thread.fpu));
 				child->thread.fpu.fcr31 = 0;
 			}
-			if (test_thread_flag(TIF_32BIT_FPREGS)) {
+			if (test_tsk_thread_flag(child, TIF_32BIT_FPREGS)) {
 				/*
 				 * The odd registers are actually the high
 				 * order bits of the values stored in the even