From: David Laight <David.Laight@ACULAB.COM>
To: 'David Howells' <dhowells@redhat.com>,
"jmorris@namei.org" <jmorris@namei.org>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
Eric Biggers <ebiggers@google.com>Aaro Koskinen
<aaro.koskinen@iki.fi>,
"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] KEYS: user: Align the payload buffer
Date: Wed, 20 Feb 2019 13:52:40 +0000 [thread overview]
Message-ID: <6bf441ffc1a54d06ad27ed01c6d06a58@AcuMS.aculab.com> (raw)
In-Reply-To: <155066953188.21038.12015964986007814182.stgit@warthog.procyon.org.uk>
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WARNING: multiple messages have this Message-ID (diff)
From: David Laight <David.Laight@ACULAB.COM>
To: 'David Howells' <dhowells@redhat.com>,
"jmorris@namei.org" <jmorris@namei.org>
Cc: Aaro Koskinen <aaro.koskinen@iki.fi>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
Eric Biggers <ebiggers@google.com>,
Aaro Koskinen <aaro.koskinen@iki.fi>,
"keyrings@vger.kernel.org" <keyrings@vger.kernel.org>,
"linux-security-module@vger.kernel.org"
<linux-security-module@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: RE: [PATCH] KEYS: user: Align the payload buffer
Date: Wed, 20 Feb 2019 13:52:40 +0000 [thread overview]
Message-ID: <6bf441ffc1a54d06ad27ed01c6d06a58@AcuMS.aculab.com> (raw)
In-Reply-To: <155066953188.21038.12015964986007814182.stgit@warthog.procyon.org.uk>
From: David Howells
> Sent: 20 February 2019 13:32
>
> From: Eric Biggers <ebiggers@google.com>
>
> Align the payload of "user" and "logon" keys so that users of the
> keyrings service can access it as a struct that requires more than
> 2-byte alignment. fscrypt currently does this which results in the read
> of fscrypt_key::size being misaligned as it needs 4-byte alignment.
>
> Align to __alignof__(u64) rather than __alignof__(long) since in the
> future it's conceivable that people would use structs beginning with
> u64, which on some platforms would require more than 'long' alignment.
...
> include/keys/user-type.h | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/include/keys/user-type.h b/include/keys/user-type.h
> index e098cbe27db5..12babe991594 100644
> --- a/include/keys/user-type.h
> +++ b/include/keys/user-type.h
> @@ -31,7 +31,7 @@
> struct user_key_payload {
> struct rcu_head rcu; /* RCU destructor */
> unsigned short datalen; /* length of this data */
> - char data[0]; /* actual data */
> + char data[0] __aligned(__alignof__(u64)); /* actual data */
> };
I'd make the 'datalen' field 'unsigned int' at the same time.
It will use some of the hole you've made and generate better
code on most arches.
David
-
Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK
Registration No: 1397386 (Wales)
next prev parent reply other threads:[~2019-02-20 13:52 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-01-15 3:37 [PATCH] KEYS: user: Align the payload buffer Eric Biggers
2019-01-15 3:37 ` Eric Biggers
2019-01-15 19:19 ` Aaro Koskinen
2019-01-15 19:19 ` Aaro Koskinen
2019-02-07 23:35 ` Eric Biggers
2019-02-07 23:35 ` Eric Biggers
2019-02-19 23:08 ` Eric Biggers
2019-02-19 23:08 ` Eric Biggers
2019-02-20 13:32 ` David Howells
2019-02-20 13:32 ` David Howells
2019-02-20 13:32 ` David Howells
2019-02-20 13:52 ` David Laight [this message]
2019-02-20 13:52 ` David Laight
2019-02-20 14:09 ` David Howells
2019-02-20 20:50 ` James Morris
2019-02-20 20:50 ` James Morris
2019-02-20 21:37 ` David Howells
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