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

[zhenwei pi]

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@xxxxxxxxxx> (maintainer:ASYMMETRIC KEYS)
> > > Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx> (maintainer:CRYPTO API)
> > > "David S. Miller" <davem@xxxxxxxxxxxxx> (maintainer:CRYPTO API)
> > > keyrings@xxxxxxxxxxxxxxx (open list:ASYMMETRIC KEYS)
> > > linux-crypto@xxxxxxxxxxxxxxx (open list:CRYPTO API)
> > > linux-kernel@xxxxxxxxxxxxxxx (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@xxxxxx"

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