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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org, Max Filippov <jcmvbkbc@gmail.com>,
        Kees Cook <keescook@chromium.org>,
        Oleg Nesterov <oleg@redhat.com>,
        "Eric W. Biederman" <ebiederm@xmission.com>
Subject: [PATCH 4.14 004/218] ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
Date:   Mon, 13 Jun 2022 12:07:42 +0200
Message-Id: <20220613094909.333855456@linuxfoundation.org>
In-Reply-To: <20220613094908.257446132@linuxfoundation.org>
References: <20220613094908.257446132@linuxfoundation.org>
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From: Eric W. Biederman <ebiederm@xmission.com>

commit 4a3d2717d140401df7501a95e454180831a0c5af upstream.

xtensa is the last user of the PT_SINGLESTEP flag.  Changing tsk->ptrace in
user_enable_single_step and user_disable_single_step without locking could
potentiallly cause problems.

So use a thread info flag instead of a flag in tsk->ptrace.  Use TIF_SINGLESTEP
that xtensa already had defined but unused.

Remove the definitions of PT_SINGLESTEP and PT_BLOCKSTEP as they have no more users.

Cc: stable@vger.kernel.org
Acked-by: Max Filippov <jcmvbkbc@gmail.com>
Tested-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Oleg Nesterov <oleg@redhat.com>
Link: https://lkml.kernel.org/r/20220505182645.497868-4-ebiederm@xmission.com
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 arch/xtensa/kernel/ptrace.c |    4 ++--
 arch/xtensa/kernel/signal.c |    4 ++--
 include/linux/ptrace.h      |    6 ------
 3 files changed, 4 insertions(+), 10 deletions(-)

--- a/arch/xtensa/kernel/ptrace.c
+++ b/arch/xtensa/kernel/ptrace.c
@@ -35,12 +35,12 @@
 
 void user_enable_single_step(struct task_struct *child)
 {
-	child->ptrace |= PT_SINGLESTEP;
+	set_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 void user_disable_single_step(struct task_struct *child)
 {
-	child->ptrace &= ~PT_SINGLESTEP;
+	clear_tsk_thread_flag(child, TIF_SINGLESTEP);
 }
 
 /*
--- a/arch/xtensa/kernel/signal.c
+++ b/arch/xtensa/kernel/signal.c
@@ -459,7 +459,7 @@ static void do_signal(struct pt_regs *re
 		/* Set up the stack frame */
 		ret = setup_frame(&ksig, sigmask_to_save(), regs);
 		signal_setup_done(ret, &ksig, 0);
-		if (current->ptrace & PT_SINGLESTEP)
+		if (test_thread_flag(TIF_SINGLESTEP))
 			task_pt_regs(current)->icountlevel = 1;
 
 		return;
@@ -485,7 +485,7 @@ static void do_signal(struct pt_regs *re
 	/* If there's no signal to deliver, we just restore the saved mask.  */
 	restore_saved_sigmask();
 
-	if (current->ptrace & PT_SINGLESTEP)
+	if (test_thread_flag(TIF_SINGLESTEP))
 		task_pt_regs(current)->icountlevel = 1;
 	return;
 }
--- a/include/linux/ptrace.h
+++ b/include/linux/ptrace.h
@@ -40,12 +40,6 @@ extern int ptrace_access_vm(struct task_
 #define PT_EXITKILL		(PTRACE_O_EXITKILL << PT_OPT_FLAG_SHIFT)
 #define PT_SUSPEND_SECCOMP	(PTRACE_O_SUSPEND_SECCOMP << PT_OPT_FLAG_SHIFT)
 
-/* single stepping state bits (used on ARM and PA-RISC) */
-#define PT_SINGLESTEP_BIT	31
-#define PT_SINGLESTEP		(1<<PT_SINGLESTEP_BIT)
-#define PT_BLOCKSTEP_BIT	30
-#define PT_BLOCKSTEP		(1<<PT_BLOCKSTEP_BIT)
-
 extern long arch_ptrace(struct task_struct *child, long request,
 			unsigned long addr, unsigned long data);
 extern int ptrace_readdata(struct task_struct *tsk, unsigned long src, char __user *dst, int len);