RE: [PATCH v2] tipc: check for null after calling kmemdup

[Xue, Ying]

Acked-by: Ying Xue <ying.xue@xxxxxxxxxxxxx>

-----Original Message-----
From: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx> 
Sent: Tuesday, November 16, 2021 12:02 AM
To: davem@xxxxxxxxxxxxx
Cc: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>; Jon Maloy <jmaloy@xxxxxxxxxx>; Xue, Ying <Ying.Xue@xxxxxxxxxxxxx>; Jakub Kicinski <kuba@xxxxxxxxxx>; netdev@xxxxxxxxxxxxxxx; tipc-discussion@xxxxxxxxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; stable@xxxxxxxxxxxxxxx; Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Subject: [PATCH v2] tipc: check for null after calling kmemdup

kmemdup can return a null pointer so need to check for it, otherwise the null key will be dereferenced later in tipc_crypto_key_xmit as can be seen in the trace [1].

Cc: Jon Maloy <jmaloy@xxxxxxxxxx>
Cc: Ying Xue <ying.xue@xxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: Jakub Kicinski <kuba@xxxxxxxxxx>
Cc: netdev@xxxxxxxxxxxxxxx
Cc: tipc-discussion@xxxxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: stable@xxxxxxxxxxxxxxx # 5.15, 5.14, 5.10

[1] https://syzkaller.appspot.com/bug?id=bca180abb29567b189efdbdb34cbf7ba851c2a58

Reported-by: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Signed-off-by: Tadeusz Struk <tadeusz.struk@xxxxxxxxxx>
---
Changed in v2:
- use tipc_aead_free() to free all crytpo tfm instances
  that might have been allocated before the fail.
---
 net/tipc/crypto.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/net/tipc/crypto.c b/net/tipc/crypto.c index dc60c32bb70d..d293614d5fc6 100644
--- a/net/tipc/crypto.c
+++ b/net/tipc/crypto.c
@@ -597,6 +597,10 @@ static int tipc_aead_init(struct tipc_aead **aead, struct tipc_aead_key *ukey,
 	tmp->cloned = NULL;
 	tmp->authsize = TIPC_AES_GCM_TAG_SIZE;
 	tmp->key = kmemdup(ukey, tipc_aead_key_size(ukey), GFP_KERNEL);
+	if (!tmp->key) {
+		tipc_aead_free(&tmp->rcu);
+		return -ENOMEM;
+	}
 	memcpy(&tmp->salt, ukey->key + keylen, TIPC_AES_GCM_SALT_SIZE);
 	atomic_set(&tmp->users, 0);
 	atomic64_set(&tmp->seqno, 0);
--
2.33.1