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

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Message-ID: <DM8PR11MB56865CBD8366FFFE28E0A6D6849A9@DM8PR11MB5686.namprd11.prod.outlook.com>
Date:   Wed, 17 Nov 2021 12:37:46 +0000
From:   "Xue, Ying" <Ying.Xue@...driver.com>
To:     Tadeusz Struk <tadeusz.struk@...aro.org>,
        "davem@...emloft.net" <davem@...emloft.net>
CC:     Jon Maloy <jmaloy@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "tipc-discussion@...ts.sourceforge.net" 
        <tipc-discussion@...ts.sourceforge.net>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "stable@...r.kernel.org" <stable@...r.kernel.org>,
        Dmitry Vyukov <dvyukov@...gle.com>
Subject: RE: [PATCH v2] tipc: check for null after calling kmemdup

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

-----Original Message-----
From: Tadeusz Struk <tadeusz.struk@...aro.org> 
Sent: Tuesday, November 16, 2021 12:02 AM
To: davem@...emloft.net
Cc: Tadeusz Struk <tadeusz.struk@...aro.org>; Jon Maloy <jmaloy@...hat.com>; Xue, Ying <Ying.Xue@...driver.com>; Jakub Kicinski <kuba@...nel.org>; netdev@...r.kernel.org; tipc-discussion@...ts.sourceforge.net; linux-kernel@...r.kernel.org; stable@...r.kernel.org; Dmitry Vyukov <dvyukov@...gle.com>
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@...hat.com>
Cc: Ying Xue <ying.xue@...driver.com>
Cc: "David S. Miller" <davem@...emloft.net>
Cc: Jakub Kicinski <kuba@...nel.org>
Cc: netdev@...r.kernel.org
Cc: tipc-discussion@...ts.sourceforge.net
Cc: linux-kernel@...r.kernel.org
Cc: stable@...r.kernel.org # 5.15, 5.14, 5.10

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

Reported-by: Dmitry Vyukov <dvyukov@...gle.com>
Signed-off-by: Tadeusz Struk <tadeusz.struk@...aro.org>
---
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