From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Subject: Re: [PATCH] dh key: fix rounding up KDF output length Date: Fri, 08 Jun 2018 16:37:58 +0100 Message-ID: <17595.1528472278@warthog.procyon.org.uk> References: <20180607191201.97080-1-ebiggers3@gmail.com> <0000000000009c221d056e0cf53a@google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Cc: dhowells@redhat.com, James Morris , keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Tycho Andersen , Kees Cook , Stephan Mueller , Eric Biggers To: Eric Biggers Return-path: In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com> Content-ID: <17594.1528472278.1@warthog.procyon.org.uk> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-crypto.vger.kernel.org Eric Biggers wrote: > Commit 383203eff718 ("dh key: get rid of stack allocated array") changed > kdf_ctr() to assume that the length of key material to derive is a > multiple of the digest size. The length was supposed to be rounded up > accordingly. However, the round_up() macro was used which only gives > the correct result on power-of-2 arguments, whereas not all hash > algorithms have power-of-2 digest sizes. In some cases this resulted in > a write past the end of the 'outbuf' buffer. > > Fix it by switching to roundup(), which works for non-power-of-2 inputs. Applied. From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Date: Fri, 08 Jun 2018 15:37:58 +0000 Subject: Re: [PATCH] dh key: fix rounding up KDF output length Message-Id: <17595.1528472278@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <20180607191201.97080-1-ebiggers3@gmail.com> <0000000000009c221d056e0cf53a@google.com> In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com> To: Eric Biggers Cc: dhowells@redhat.com, James Morris , keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, Tycho Andersen , Kees Cook , Stephan Mueller , Eric Biggers Eric Biggers wrote: > Commit 383203eff718 ("dh key: get rid of stack allocated array") changed > kdf_ctr() to assume that the length of key material to derive is a > multiple of the digest size. The length was supposed to be rounded up > accordingly. However, the round_up() macro was used which only gives > the correct result on power-of-2 arguments, whereas not all hash > algorithms have power-of-2 digest sizes. In some cases this resulted in > a write past the end of the 'outbuf' buffer. > > Fix it by switching to roundup(), which works for non-power-of-2 inputs. Applied. From mboxrd@z Thu Jan 1 00:00:00 1970 From: dhowells@redhat.com (David Howells) Date: Fri, 08 Jun 2018 16:37:58 +0100 Subject: [PATCH] dh key: fix rounding up KDF output length In-Reply-To: <20180607191201.97080-1-ebiggers3@gmail.com> References: <20180607191201.97080-1-ebiggers3@gmail.com> <0000000000009c221d056e0cf53a@google.com> Message-ID: <17595.1528472278@warthog.procyon.org.uk> To: linux-security-module@vger.kernel.org List-Id: linux-security-module.vger.kernel.org Eric Biggers wrote: > Commit 383203eff718 ("dh key: get rid of stack allocated array") changed > kdf_ctr() to assume that the length of key material to derive is a > multiple of the digest size. The length was supposed to be rounded up > accordingly. However, the round_up() macro was used which only gives > the correct result on power-of-2 arguments, whereas not all hash > algorithms have power-of-2 digest sizes. In some cases this resulted in > a write past the end of the 'outbuf' buffer. > > Fix it by switching to roundup(), which works for non-power-of-2 inputs. Applied. -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html