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SubjectRe: Re: Re: PING: [PATCH] crypto: public_key: fix overflow during implicit conversion
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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@redhat.com> (maintainer:ASYMMETRIC KEYS)
>>> Herbert Xu <herbert@gondor.apana.org.au> (maintainer:CRYPTO API)
>>> "David S. Miller" <davem@davemloft.net> (maintainer:CRYPTO API)
>>> keyrings@vger.kernel.org (open list:ASYMMETRIC KEYS)
>>> linux-crypto@vger.kernel.org (open list:CRYPTO API)
>>> linux-kernel@vger.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@xx.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

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