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Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: References: <20260105152145.1801972-1-dhowells@redhat.com> <20260105152145.1801972-3-dhowells@redhat.com> To: Ignat Korchagin Cc: dhowells@redhat.com, Lukas Wunner , Jarkko Sakkinen , Herbert Xu , Eric Biggers , Luis Chamberlain , Petr Pavlu , Daniel Gomez , Sami Tolvanen , "Jason A . Donenfeld" , Ard Biesheuvel , Stephan Mueller , linux-crypto@vger.kernel.org, keyrings@vger.kernel.org, linux-modules@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v11 2/8] pkcs7: Allow the signing algo to calculate the digest itself Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <2366239.1767794004.1@warthog.procyon.org.uk> Content-Transfer-Encoding: quoted-printable Date: Wed, 07 Jan 2026 13:53:24 +0000 Message-ID: <2366240.1767794004@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.93 Ignat Korchagin wrote: > > + ret =3D -ENOMEM; > > + sig->digest =3D kmalloc(umax(sinfo->authattrs_= len, sig->digest_size), > > + GFP_KERNEL); > = > Can we refactor this so we allocate the right size from the start. The problem is that we don't know the right size until we've tried parsing= it. > Alternatively, should we just unconditionally use this approach > "overallocating" some times? In some ways, what I'd rather do is push the hash calculation down into th= e crypto/ layer for all public key algos. Also, we probably don't actually need to copy the authattrs, just retain a pointer into the source buffer and the length since we don't intend to kee= p the digest around beyond the verification procedure. So I might be able t= o get away with just a flag saying I don't need to free it. However, there's an intermediate hash if there are authattrs, so I will ne= ed to store that somewhere - though that could be allocated on demand. David