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From:   Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To:     linux-kernel@vger.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        stable@vger.kernel.org,
        Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>,
        syzbot+9de458f6a5e713ee8c1a@syzkaller.appspotmail.com,
        Theodore Tso <tytso@mit.edu>
Subject: [PATCH 4.9 06/61] random: fix possible sleeping allocation from irq context
Date:   Mon, 30 Apr 2018 12:24:09 -0700
Message-Id: <20180430183951.848308311@linuxfoundation.org>
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4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Theodore Ts'o <tytso@mit.edu>

commit 6c1e851c4edc13a43adb3ea4044e3fc8f43ccf7d upstream.

We can do a sleeping allocation from an irq context when CONFIG_NUMA
is enabled.  Fix this by initializing the NUMA crng instances in a
workqueue.

Reported-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Reported-by: syzbot+9de458f6a5e713ee8c1a@syzkaller.appspotmail.com
Fixes: 8ef35c866f8862df ("random: set up the NUMA crng instances...")
Cc: stable@vger.kernel.org
Signed-off-by: Theodore Ts'o <tytso@mit.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/char/random.c |    9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -820,7 +820,7 @@ static int crng_fast_load(const char *cp
 }
 
 #ifdef CONFIG_NUMA
-static void numa_crng_init(void)
+static void do_numa_crng_init(struct work_struct *work)
 {
 	int i;
 	struct crng_state *crng;
@@ -841,6 +841,13 @@ static void numa_crng_init(void)
 		kfree(pool);
 	}
 }
+
+static DECLARE_WORK(numa_crng_init_work, do_numa_crng_init);
+
+static void numa_crng_init(void)
+{
+	schedule_work(&numa_crng_init_work);
+}
 #else
 static void numa_crng_init(void) {}
 #endif