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

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Message-ID: <8bf3a04d-f1a7-cd8c-5c5a-ace3de500b2f@bytedance.com>
Date:   Thu, 19 Aug 2021 10:03:48 +0800
From:   zhenwei pi <pizhenwei@...edance.com>
To:     Jarkko Sakkinen <jarkko.sakkinen@....fi>, 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
Subject: Re: Re: PING: [PATCH] crypto: public_key: fix overflow during
 implicit conversion

On 8/18/21 8:33 PM, Jarkko Sakkinen wrote:
> On Wed, 2021-08-18 at 16:33 +0800, zhenwei pi wrote:
>> PING
> 
> Please, do not top-post.
> 
> You are lacking Herbert Xu:
> 
> $ scripts/get_maintainer.pl crypto/asymmetric_keys/public_key.c
> David Howells <dhowells@...hat.com> (maintainer:ASYMMETRIC KEYS)
> Herbert Xu <herbert@...dor.apana.org.au> (maintainer:CRYPTO API)
> "David S. Miller" <davem@...emloft.net> (maintainer:CRYPTO API)
> keyrings@...r.kernel.org (open list:ASYMMETRIC KEYS)
> linux-crypto@...r.kernel.org (open list:CRYPTO API)
> linux-kernel@...r.kernel.org (open list)
> 
>> On 8/10/21 2:39 PM, zhenwei pi wrote:
>>> 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
> 
> Where is this statement?
> 

In function "static int asymmetric_key_verify_signature(struct 
kernel_pkey_params *params, const void *in, const void *in2)"

>>> 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.
>                                                       ~~~~~
>                                                       64-bit
>                                                       
> What do you mean by "could"? Does it, or does it
> not?
>                                         					
> 
After reordering struct public_key_signature, sizeof(struct 
public_key_signature) gets smaller than the original version.
	  								
> 									
> 		
> 
>>>
>>> Signed-off-by: zhenwei pi <pizhenwei@...edance.com>
> 
> Nit: "Firstname Lastname" (first letters capitalized)
> 
>>> ---
>>>    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;
>>>
> 
> /Jarkko
> 

-- 
zhenwei pi