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kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve 

This changes kcmp_epoll_target to use the new exec_update_mutex
instead of cred_guard_mutex.

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

Signed-off-by: Bernd Edlinger <bernd.edlinger@hotmail.de>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
This commit is contained in:
Bernd Edlinger 2020-03-20 21:27:05 +01:00 committed by Eric W. Biederman
parent aa884c1131
commit 454e3126cb
1 changed files with 4 additions and 4 deletions
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8
kernel/kcmp.c
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@ -173,8 +173,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
/*
* One should have enough rights to inspect task details.
*/
ret = kcmp_lock(&task1->signal->cred_guard_mutex,
&task2->signal->cred_guard_mutex);
ret = kcmp_lock(&task1->signal->exec_update_mutex,
&task2->signal->exec_update_mutex);
if (ret)
goto err;
if (!ptrace_may_access(task1, PTRACE_MODE_READ_REALCREDS) ||
@ -229,8 +229,8 @@ SYSCALL_DEFINE5(kcmp, pid_t, pid1, pid_t, pid2, int, type,
}
err_unlock:
kcmp_unlock(&task1->signal->cred_guard_mutex,
&task2->signal->cred_guard_mutex);
kcmp_unlock(&task1->signal->exec_update_mutex,
&task2->signal->exec_update_mutex);
err:
put_task_struct(task1);
put_task_struct(task2);