[PATCH] random: fix possible sleeping allocation from irq context

Theodore Ts'o
2018-04-24T03:41:47Z

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

diff --git a/drivers/char/random.c b/drivers/char/random.c
index 3cd3aae24d6d..e182cca7e6cd 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -789,7 +789,7 @@ static void crng_initialize(struct crng_state *crng)
}

#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;
@@ -810,6 +810,13 @@ static void numa_crng_init(void)
kfree(pool);
}
}
+
+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
--
2.16.1.72.g5be1f00a9a