linux-kernel - [PATCH] crypto: public_key: fix overflow during implicit conversion

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Date:   Tue, 10 Aug 2021 14:39:54 +0800
From:   zhenwei pi <pizhenwei@...edance.com>
To:     dhowells@...hat.com, herbert@...dor.apana.org.au,
        davem@...emloft.net
Cc:     keyrings@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-kernel@...r.kernel.org, zhenwei pi <pizhenwei@...edance.com>
Subject: [PATCH] crypto: public_key: fix overflow during implicit conversion

Hit kernel warning like this, it can be reproduced by verifying 256
bytes datafile by keyctl command.

 WARNING: CPU: 5 PID: 344556 at crypto/rsa-pkcs1pad.c:540 pkcs1pad_verify+0x160/0x190
 ...
 Call Trace:
  public_key_verify_signature+0x282/0x380
  ? software_key_query+0x12d/0x180
  ? keyctl_pkey_params_get+0xd6/0x130
  asymmetric_key_verify_signature+0x66/0x80
  keyctl_pkey_verify+0xa5/0x100
  do_syscall_64+0x35/0xb0
  entry_SYSCALL_64_after_hwframe+0x44/0xae

'.digest_size(u8) = params->in_len(u32)' leads overflow of an u8 value,
so use u32 instead of u8 of digest. And reorder struct
public_key_signature, it could save 8 bytes on a 64 bit machine.

Signed-off-by: zhenwei pi <pizhenwei@...edance.com>
---
 include/crypto/public_key.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/crypto/public_key.h b/include/crypto/public_key.h
index 47accec68cb0..f603325c0c30 100644
--- a/include/crypto/public_key.h
+++ b/include/crypto/public_key.h
@@ -38,9 +38,9 @@ extern void public_key_free(struct public_key *key);
 struct public_key_signature {
 	struct asymmetric_key_id *auth_ids[2];
 	u8 *s;			/* Signature */
-	u32 s_size;		/* Number of bytes in signature */
 	u8 *digest;
-	u8 digest_size;		/* Number of bytes in digest */
+	u32 s_size;		/* Number of bytes in signature */
+	u32 digest_size;	/* Number of bytes in digest */
 	const char *pkey_algo;
 	const char *hash_algo;
 	const char *encoding;
-- 
2.25.1