linux-kernel - [PATCH] KEYS: prevent NULL pointer dereference in find_asymmetric

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Message-ID: <20240315103320.18754-1-r.smirnov@omp.ru>
Date: Fri, 15 Mar 2024 13:33:20 +0300
From: Roman Smirnov <r.smirnov@....ru>
To: David Howells <dhowells@...hat.com>, Herbert Xu
	<herbert@...dor.apana.org.au>, "David S. Miller" <davem@...emloft.net>,
	Jarkko Sakkinen <jarkko@...nel.org>, Andrew Zaborowski
	<andrew.zaborowski@...el.com>
CC: Roman Smirnov <r.smirnov@....ru>, <keyrings@...r.kernel.org>,
	<linux-crypto@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<lvc-project@...uxtesting.org>, Sergey Shtylyov <s.shtylyov@....ru>
Subject: [PATCH] KEYS: prevent NULL pointer dereference in find_asymmetric_key()

With the current code, in case all NULLs are passed in id_{0,1,2},
the kernel will first print out a WARNING and then have an oops
because id_2 gets dereferenced anyway.
Note that WARN_ON() is also considered harmful by Greg Kroah-
Hartman since it causes the Android kernels to panic as they
get booted with the panic_on_warn option.

Found by Linux Verification Center (linuxtesting.org) with Svace.

Fixes: 7d30198ee24f ("keys: X.509 public key issuer lookup without AKID")
Suggested-by: Sergey Shtylyov <s.shtylyov@....ru>
Signed-off-by: Roman Smirnov <r.smirnov@....ru>
Reviewed-by: Sergey Shtylyov <s.shtylyov@....ru>
---
 crypto/asymmetric_keys/asymmetric_type.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/crypto/asymmetric_keys/asymmetric_type.c b/crypto/asymmetric_keys/asymmetric_type.c
index a5da8ccd353e..f5cbd6ff14e2 100644
--- a/crypto/asymmetric_keys/asymmetric_type.c
+++ b/crypto/asymmetric_keys/asymmetric_type.c
@@ -60,17 +60,17 @@ struct key *find_asymmetric_key(struct key *keyring,
 	char *req, *p;
 	int len;
 
-	WARN_ON(!id_0 && !id_1 && !id_2);
-
 	if (id_0) {
 		lookup = id_0->data;
 		len = id_0->len;
 	} else if (id_1) {
 		lookup = id_1->data;
 		len = id_1->len;
-	} else {
+	} else if (id_2) {
 		lookup = id_2->data;
 		len = id_2->len;
+	} else {
+		return ERR_PTR(-EINVAL);
 	}
 
 	/* Construct an identifier "id:<keyid>". */
-- 
2.34.1