--- /dev/null
+From 6a2d90ba027adba528509ffa27097cffd3879257 Mon Sep 17 00:00:00 2001
+From: "Eric W. Biederman" <ebiederm@xmission.com>
+Date: Fri, 29 Apr 2022 09:23:55 -0500
+Subject: ptrace: Reimplement PTRACE_KILL by always sending SIGKILL
+
+From: Eric W. Biederman <ebiederm@xmission.com>
+
+commit 6a2d90ba027adba528509ffa27097cffd3879257 upstream.
+
+The current implementation of PTRACE_KILL is buggy and has been for
+many years as it assumes it's target has stopped in ptrace_stop. At a
+quick skim it looks like this assumption has existed since ptrace
+support was added in linux v1.0.
+
+While PTRACE_KILL has been deprecated we can not remove it as
+a quick search with google code search reveals many existing
+programs calling it.
+
+When the ptracee is not stopped at ptrace_stop some fields would be
+set that are ignored except in ptrace_stop. Making the userspace
+visible behavior of PTRACE_KILL a noop in those case.
+
+As the usual rules are not obeyed it is not clear what the
+consequences are of calling PTRACE_KILL on a running process.
+Presumably userspace does not do this as it achieves nothing.
+
+Replace the implementation of PTRACE_KILL with a simple
+send_sig_info(SIGKILL) followed by a return 0. This changes the
+observable user space behavior only in that PTRACE_KILL on a process
+not stopped in ptrace_stop will also kill it. As that has always
+been the intent of the code this seems like a reasonable change.
+
+Cc: stable@vger.kernel.org
+Reported-by: Al Viro <viro@zeniv.linux.org.uk>
+Suggested-by: Al Viro <viro@zeniv.linux.org.uk>
+Tested-by: Kees Cook <keescook@chromium.org>
+Reviewed-by: Oleg Nesterov <oleg@redhat.com>
+Link: https://lkml.kernel.org/r/20220505182645.497868-7-ebiederm@xmission.com
+Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ arch/x86/kernel/step.c | 3 +--
+ kernel/ptrace.c | 5 ++---
+ 2 files changed, 3 insertions(+), 5 deletions(-)
+
+--- a/arch/x86/kernel/step.c
++++ b/arch/x86/kernel/step.c
+@@ -175,8 +175,7 @@ void set_task_blockstep(struct task_stru
+ *
+ * NOTE: this means that set/clear TIF_BLOCKSTEP is only safe if
+ * task is current or it can't be running, otherwise we can race
+- * with __switch_to_xtra(). We rely on ptrace_freeze_traced() but
+- * PTRACE_KILL is not safe.
++ * with __switch_to_xtra(). We rely on ptrace_freeze_traced().
+ */
+ local_irq_disable();
+ debugctl = get_debugctlmsr();
+--- a/kernel/ptrace.c
++++ b/kernel/ptrace.c
+@@ -1127,9 +1127,8 @@ int ptrace_request(struct task_struct *c
+ return ptrace_resume(child, request, data);
+
+ case PTRACE_KILL:
+- if (child->exit_state) /* already dead */
+- return 0;
+- return ptrace_resume(child, request, SIGKILL);
++ send_sig_info(SIGKILL, SEND_SIG_NOINFO, child);
++ return 0;
+
+ #ifdef CONFIG_HAVE_ARCH_TRACEHOOK
+ case PTRACE_GETREGSET:
--- /dev/null
+From 4a3d2717d140401df7501a95e454180831a0c5af Mon Sep 17 00:00:00 2001
+From: "Eric W. Biederman" <ebiederm@xmission.com>
+Date: Tue, 26 Apr 2022 16:45:37 -0500
+Subject: ptrace/xtensa: Replace PT_SINGLESTEP with TIF_SINGLESTEP
+
+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);
projects / thirdparty / kernel / stable-queue.git / commitdiff
