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Subject[PATCH v6 11/16] proc: Use new infrastructure to fix deadlocks in execve
Date
This changes lock_trace to use the new exec_update_mutex
instead of cred_guard_mutex.

This fixes possible deadlocks when the trace is accessing
/proc/$pid/stack for instance.

This should be safe, as the credentials are only used for reading,
and task->mm is updated on execve under the new exec_update_mutex.

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
---
fs/proc/base.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/fs/proc/base.c b/fs/proc/base.c
index c7c6427..fed76abf 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -405,11 +405,11 @@ static int proc_pid_wchan(struct seq_file *m, struct pid_namespace *ns,

static int lock_trace(struct task_struct *task)
{
- int err = mutex_lock_killable(&task->signal->cred_guard_mutex);
+ int err = mutex_lock_killable(&task->signal->exec_update_mutex);
if (err)
return err;
if (!ptrace_may_access(task, PTRACE_MODE_ATTACH_FSCREDS)) {
- mutex_unlock(&task->signal->cred_guard_mutex);
+ mutex_unlock(&task->signal->exec_update_mutex);
return -EPERM;
}
return 0;
@@ -417,7 +417,7 @@ static int lock_trace(struct task_struct *task)

static void unlock_trace(struct task_struct *task)
{
- mutex_unlock(&task->signal->cred_guard_mutex);
+ mutex_unlock(&task->signal->exec_update_mutex);
}

#ifdef CONFIG_STACKTRACE
--
1.9.1
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