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

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Message-ID: <7ae0836f-884b-e262-6ade-d0ca6ea0eb93@bytedance.com>
Date:   Thu, 19 Aug 2021 18:52:23 +0800
From:   zhenwei pi <pizhenwei@...edance.com>
To:     Jarkko Sakkinen <jarkko@...nel.org>, 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: Re: PING: [PATCH] crypto: public_key: fix overflow during
 implicit conversion

On 8/19/21 6:35 PM, Jarkko Sakkinen wrote:
> On Thu, 2021-08-19 at 10:03 +0800, zhenwei pi wrote:
>> 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.
> 
> OK, then just state is as "it saves" instead of "it could save".
> 
> Not a requirement but have you been able to trigger this for a
> kernel that does not have this fix?
> 
This kernel warning can be reproduced on debian11(Linux-5.10.0-8-amd64) 
by the following script:

RAWDATA=rawdata
SIGDATA=sigdata

modprobe pkcs8_key_parser

rm -rf *.der *.pem *.pfx
rm -rf $RAWDATA
dd if=/dev/random of=$RAWDATA bs=256 count=1

openssl req -nodes -x509 -newkey rsa:4096 -keyout key.pem -out cert.pem 
-subj "/C=CN/ST=GD/L=SZ/O=vihoo/OU=dev/CN=xx.com/emailAddress=yy@...com"

KEY_ID=`openssl pkcs8 -in key.pem -topk8 -nocrypt -outform DER | keyctl 
padd asymmetric 123 @s`

keyctl pkey_sign $KEY_ID 0 $RAWDATA enc=pkcs1 hash=sha1 > $SIGDATA
keyctl pkey_verify $KEY_ID 0 $RAWDATA $SIGDATA enc=pkcs1 hash=sha1


> /Jarkko
> 

-- 
zhenwei pi