From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: akpm@linux-foundation.org, mbligh@google.com,
linux-kernel@vger.kernel.org, davem@davemloft.net,
sparclinux@vger.kernel.org
Subject: [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
Date: Fri, 09 Mar 2007 02:38:14 +0000 [thread overview]
Message-ID: <20070309023814.GA9462@Krystal> (raw)
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
WARNING: multiple messages have this Message-ID (diff)
From: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
To: akpm@linux-foundation.org, mbligh@google.com,
linux-kernel@vger.kernel.org, davem@davemloft.net,
sparclinux@vger.kernel.org
Subject: [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64
Date: Thu, 8 Mar 2007 21:38:14 -0500 [thread overview]
Message-ID: <20070309023814.GA9462@Krystal> (raw)
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
next reply other threads:[~2007-03-09 2:38 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-09 2:38 Mathieu Desnoyers [this message]
2007-03-09 2:38 ` [PATCH] Fix atomicity of TIF update in flush_thread() for sparc64 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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