Re: [PATCH v2 2/6] smb: clear the aes_cmac_key and aes_cmac_ctx when done

[Namjae Jeon]

On Tue, Aug 11, 2026 at 9:57 PM Thomas Huth <thuth@xxxxxxxxxx> wrote:
>
> On 11/08/2026 12.31, Namjae Jeon wrote:
> >> diff --git a/fs/smb/client/smb2transport.c b/fs/smb/client/smb2transport.c
> >> index 1143ee52470a7..d23566da2ac81 100644
> >> --- a/fs/smb/client/smb2transport.c
> >> +++ b/fs/smb/client/smb2transport.c
> >> @@ -464,8 +464,8 @@ smb3_calc_signature(struct smb_rqst *rqst, struct TCP_Server_Info *server)
> >>          unsigned char smb3_signature[SMB2_CMACAES_SIZE];
> >>          struct kvec *iov = rqst->rq_iov;
> >>          struct smb2_hdr *shdr = (struct smb2_hdr *)iov[0].iov_base;
> >> -       struct aes_cmac_key cmac_key;
> >> -       struct aes_cmac_ctx cmac_ctx;
> >> +       struct aes_cmac_key cmac_key __cleanup(aes_cmac_zeroize_key);
> >> +       struct aes_cmac_ctx cmac_ctx __cleanup(aes_cmac_zeroize_ctx);
> >>          struct smb_rqst drqst;
> >>          u8 key[SMB3_SIGN_KEY_SIZE];
> > Shouldn’t we also clear the raw key with memzero_explicit(key,
> > sizeof(key)) immediately after aes_cmac_preparekey() ?
> >
> >          rc = aes_cmac_preparekey(&cmac_key, key, SMB2_CMACAES_SIZE);
> > +        memzero_explicit(key, sizeof(key));
> >          if (rc) {
> >                  cifs_server_dbg(VFS, "%s: Could not set key for cmac
> > aes\n", __func__);
> >                  return rc;
> >          }
> Yes, but I was planning to do all the scrubbing for such other spots in a
> separate patch series (similar to what I've posted for the smb/server code
> already) ... this patch series here focuses on aes_cmac_zeroize_key and
> aes_cmac_zeroize_ctx only. I hope that's ok?
Acked-by: Namjae Jeon <linkinjeon@xxxxxxxxxx>
Thanks.