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

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Date:   Wed, 18 Aug 2021 15:33:32 +0300
From:   Jarkko Sakkinen <jarkko.sakkinen@....fi>
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: PING: [PATCH] crypto: public_key: fix overflow during implicit
 conversion

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?

> > 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?                                                                   
                                       					
	  								
									
		

> > 
> > 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