Re: [tipc-discussion] [PATCH v2] tipc: check for null after calling kmemdup

[Xue, Y. <Yin...@wi...>]

Acked-by: Ying Xue <yin...@wi...>

-----Original Message-----
From: Tadeusz Struk <tad...@li...> 
Sent: Tuesday, November 16, 2021 12:02 AM
To: da...@da...
Cc: Tadeusz Struk <tad...@li...>; Jon Maloy <jm...@re...>; Xue, Ying <Yin...@wi...>; Jakub Kicinski <ku...@ke...>; ne...@vg...; tip...@li...; lin...@vg...; st...@vg...; Dmitry Vyukov <dv...@go...>
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 <jm...@re...>
Cc: Ying Xue <yin...@wi...>
Cc: "David S. Miller" <da...@da...>
Cc: Jakub Kicinski <ku...@ke...>
Cc: ne...@vg...
Cc: tip...@li...
Cc: lin...@vg...
Cc: st...@vg... # 5.15, 5.14, 5.10

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

Reported-by: Dmitry Vyukov <dv...@go...>
Signed-off-by: Tadeusz Struk <tad...@li...>
---
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