kernel/kcmp.c: Use new infrastructure to fix deadlocks in execve (454e3126) · Commits · 戴 / test

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>

kernel/kcmp.c

+4 −4

Original line number	Diff line number	Diff line
		@@ -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);

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