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

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Message-ID: <94672b79411362d524455cca4680d3d28f1ec376.camel@kernel.org>
Date:   Thu, 19 Aug 2021 14:44:26 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     zhenwei pi <pizhenwei@...edance.com>, 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 Thu, 2021-08-19 at 18:52 +0800, zhenwei pi wrote:
> 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


Thank you. I'll see if I can reproduce this when you send a new version
(if not, it is not constraint for accepting to patch, but I'll still
try).

PS. Ignore the firstname lastname comment. I was not aware that in some
cultures it is written like that (James Bottomley pointed this out).

/Jarkko