[PATCH] Fix atomicity of TIF update in flush

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* [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-09  2:38 ` Mathieu Desnoyers
  0 siblings, 0 replies; 8+ messages in thread
From: Mathieu Desnoyers @ 2007-03-09  2:38 UTC (permalink / raw)
  To: akpm, mbligh, linux-kernel, davem, sparclinux

Fix atomicity of TIF update in flush_thread() for x86_64

Race :

parent process executing :
sys_ptrace()
 (lock_kernel())
 (ptrace_get_task_struct(pid))
 arch_ptrace()
   ptrace_detach()
     ptrace_disable(child);
       clear_singlestep(child);
         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
         (which clears the TIF_SINGLESTEP flag atomically from a different
	  process)
 (put_task_struct(child))
 (unlock_kernel())

And at the same time, in the child process :
sys_execve()
 do_execve()
   search_binary_handler()
     load_elf_binary()
       flush_old_exec()
         flush_thread()
           doing a non-atomic thread flag update 

It applies on 2.6.20.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/arch/sparc64/kernel/process.c
+++ b/arch/sparc64/kernel/process.c
@@ -413,8 +413,13 @@ void flush_thread(void)
 	struct thread_info *t = current_thread_info();
 	struct mm_struct *mm;
 
-	if (t->flags & _TIF_ABI_PENDING)
-		t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
+	if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
+		clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
+		if (test_tsk_thread_flag(tsk, TIF_32BIT))
+			clear_tsk_thread_flag(tsk, TIF_32BIT);
+		else
+			set_tsk_thread_flag(tsk, TIF_32BIT);
+	}
 
 	mm = t->task->mm;
 	if (mm)
-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-09  2:38 ` Mathieu Desnoyers
  0 siblings, 0 replies; 8+ messages in thread
From: Mathieu Desnoyers @ 2007-03-09  2:38 UTC (permalink / raw)
  To: akpm, mbligh, linux-kernel, davem, sparclinux

Fix atomicity of TIF update in flush_thread() for x86_64

Race :

parent process executing :
sys_ptrace()
 (lock_kernel())
 (ptrace_get_task_struct(pid))
 arch_ptrace()
   ptrace_detach()
     ptrace_disable(child);
       clear_singlestep(child);
         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
         (which clears the TIF_SINGLESTEP flag atomically from a different
	  process)
 (put_task_struct(child))
 (unlock_kernel())

And at the same time, in the child process :
sys_execve()
 do_execve()
   search_binary_handler()
     load_elf_binary()
       flush_old_exec()
         flush_thread()
           doing a non-atomic thread flag update 

It applies on 2.6.20.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/arch/sparc64/kernel/process.c
+++ b/arch/sparc64/kernel/process.c
@@ -413,8 +413,13 @@ void flush_thread(void)
 	struct thread_info *t = current_thread_info();
 	struct mm_struct *mm;
 
-	if (t->flags & _TIF_ABI_PENDING)
-		t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
+	if (test_tsk_thread_flag(tsk, TIF_ABI_PENDING)) {
+		clear_tsk_thread_flag(tsk, TIF_ABI_PENDING);
+		if (test_tsk_thread_flag(tsk, TIF_32BIT))
+			clear_tsk_thread_flag(tsk, TIF_32BIT);
+		else
+			set_tsk_thread_flag(tsk, TIF_32BIT);
+	}
 
 	mm = t->task->mm;
 	if (mm)
-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] Fix atomicity of TIF update in flush_thread() for
  2007-03-09  2:38 ` Mathieu Desnoyers
@ 2007-03-09  5:24   ` David Miller
  -1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2007-03-09  5:24 UTC (permalink / raw)
  To: mathieu.desnoyers; +Cc: akpm, mbligh, linux-kernel, sparclinux

From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Thu, 8 Mar 2007 21:38:14 -0500

> Fix atomicity of TIF update in flush_thread() for x86_64
                                                    ^^^^^^
You mean sparc64 of course, I fixed this up while committing your
patch, thanks a lot.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-09  5:24   ` David Miller
  0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2007-03-09  5:24 UTC (permalink / raw)
  To: mathieu.desnoyers; +Cc: akpm, mbligh, linux-kernel, sparclinux

From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Date: Thu, 8 Mar 2007 21:38:14 -0500

> Fix atomicity of TIF update in flush_thread() for x86_64
                                                    ^^^^^^
You mean sparc64 of course, I fixed this up while committing your
patch, thanks a lot.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-10  8:08   ` Mathieu Desnoyers
  0 siblings, 0 replies; 8+ messages in thread
From: Mathieu Desnoyers @ 2007-03-10  8:08 UTC (permalink / raw)
  To: akpm, mbligh, linux-kernel, davem, sparclinux

Fix atomicity of TIF update in flush_thread() for sparc64

Fixes correctly the race by using *_ti_thread_flag.

Race :

parent process executing :
sys_ptrace()
 (lock_kernel())
 (ptrace_get_task_struct(pid))
 arch_ptrace()
   ptrace_detach()
     ptrace_disable(child);
       clear_singlestep(child);
         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
         (which clears the TIF_SINGLESTEP flag atomically from a different
          process)
 (put_task_struct(child))
 (unlock_kernel())

And at the same time, in the child process :
sys_execve()
 do_execve()
   search_binary_handler()
     load_elf_binary()
       flush_old_exec()
         flush_thread()
           doing a non-atomic thread flag update

It applies on 2.6.20.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/arch/sparc64/kernel/process.c
+++ b/arch/sparc64/kernel/process.c
@@ -413,8 +413,13 @@ void flush_thread(void)
 	struct thread_info *t = current_thread_info();
 	struct mm_struct *mm;
 
-	if (t->flags & _TIF_ABI_PENDING)
-		t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
+	if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
+		clear_ti_thread_flag(t, TIF_ABI_PENDING);
+		if (test_ti_thread_flag(t, TIF_32BIT))
+			clear_ti_thread_flag(t, TIF_32BIT);
+		else
+			set_ti_thread_flag(t, TIF_32BIT);
+	}
 
 	mm = t->task->mm;
 	if (mm)
-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

^ permalink raw reply	[flat|nested] 8+ messages in thread

* [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-10  8:08   ` Mathieu Desnoyers
  0 siblings, 0 replies; 8+ messages in thread
From: Mathieu Desnoyers @ 2007-03-10  8:08 UTC (permalink / raw)
  To: akpm, mbligh, linux-kernel, davem, sparclinux

Fix atomicity of TIF update in flush_thread() for sparc64

Fixes correctly the race by using *_ti_thread_flag.

Race :

parent process executing :
sys_ptrace()
 (lock_kernel())
 (ptrace_get_task_struct(pid))
 arch_ptrace()
   ptrace_detach()
     ptrace_disable(child);
       clear_singlestep(child);
         clear_tsk_thread_flag(child, TIF_SINGLESTEP);
         (which clears the TIF_SINGLESTEP flag atomically from a different
          process)
 (put_task_struct(child))
 (unlock_kernel())

And at the same time, in the child process :
sys_execve()
 do_execve()
   search_binary_handler()
     load_elf_binary()
       flush_old_exec()
         flush_thread()
           doing a non-atomic thread flag update

It applies on 2.6.20.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>

--- a/arch/sparc64/kernel/process.c
+++ b/arch/sparc64/kernel/process.c
@@ -413,8 +413,13 @@ void flush_thread(void)
 	struct thread_info *t = current_thread_info();
 	struct mm_struct *mm;
 
-	if (t->flags & _TIF_ABI_PENDING)
-		t->flags ^= (_TIF_ABI_PENDING | _TIF_32BIT);
+	if (test_ti_thread_flag(t, TIF_ABI_PENDING)) {
+		clear_ti_thread_flag(t, TIF_ABI_PENDING);
+		if (test_ti_thread_flag(t, TIF_32BIT))
+			clear_ti_thread_flag(t, TIF_32BIT);
+		else
+			set_ti_thread_flag(t, TIF_32BIT);
+	}
 
 	mm = t->task->mm;
 	if (mm)
-- 
Mathieu Desnoyers
Computer Engineering Ph.D. Student, Ecole Polytechnique de Montreal
OpenPGP key fingerprint: 8CD5 52C3 8E3C 4140 715F  BA06 3F25 A8FE 3BAE 9A68

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] Fix atomicity of TIF update in flush_thread() for
  2007-03-10  8:08   ` Mathieu Desnoyers
@ 2007-03-10  8:28     ` David Miller
  -1 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2007-03-10  8:28 UTC (permalink / raw)
  To: compudj; +Cc: akpm, mbligh, linux-kernel, sparclinux

From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Date: Sat, 10 Mar 2007 03:08:44 -0500

> Fix atomicity of TIF update in flush_thread() for sparc64

Applied, thanks for fixing this up.

^ permalink raw reply	[flat|nested] 8+ messages in thread

* Re: [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
@ 2007-03-10  8:28     ` David Miller
  0 siblings, 0 replies; 8+ messages in thread
From: David Miller @ 2007-03-10  8:28 UTC (permalink / raw)
  To: compudj; +Cc: akpm, mbligh, linux-kernel, sparclinux

From: Mathieu Desnoyers <compudj@krystal.dyndns.org>
Date: Sat, 10 Mar 2007 03:08:44 -0500

> Fix atomicity of TIF update in flush_thread() for sparc64

Applied, thanks for fixing this up.

^ permalink raw reply	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2007-03-10  8:28 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2007-03-09  2:38 [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64 Mathieu Desnoyers
2007-03-09  2:38 ` Mathieu Desnoyers
2007-03-09  5:24 ` [PATCH] Fix atomicity of TIF update in flush_thread() for David Miller
2007-03-09  5:24   ` [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64 David Miller
2007-03-10  8:08 ` Mathieu Desnoyers
2007-03-10  8:08   ` Mathieu Desnoyers
2007-03-10  8:28   ` [PATCH] Fix atomicity of TIF update in flush_thread() for David Miller
2007-03-10  8:28     ` [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64 David Miller

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