On 30-Aug-2019, at 2:26 PM, Hillf Danton [off-list ref] wrote:


On Fri, 30 Aug 2019 12:18:07 +0530 Sachin Sant wrote:

quoted

[ 8074.351033] BUG: Kernel NULL pointer dereference at 0x00000038
[ 8074.351046] Faulting instruction address: 0xc0000000004ddf30
[ 8074.351052] Oops: Kernel access of bad area, sig: 11 [#1]
[ 8074.351056] LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries

Add rcu gp.

--- a/security/keys/request_key_auth.c
+++ b/security/keys/request_key_auth.c

@@ -64,12 +64,19 @@ static int request_key_auth_instantiate(

static void request_key_auth_describe(const struct key *key,
				      struct seq_file *m)
{
-	struct request_key_auth *rka = dereference_key_rcu(key);
+	struct request_key_auth *rka;
+
+	rcu_read_lock();
+	rka = dereference_key_rcu(key);
+	if (!rka)
+		goto out;