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

[zhenwei pi]

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.
	  								
> 									
> 		
>
> > > Signed-off-by: zhenwei pi <pizhenwei@xxxxxxxxxxxxx>
>
> 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

--
zhenwei pi