RE: [PATCH] KEYS: user: Align the payload buffer
From: David Laight <hidden>
Date: 2019-02-20 13:52:03
Also in:
keyrings, lkml, stable
From: David Howells
Sent: 20 February 2019 13:32 From: Eric Biggers <redacted> 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.
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quoted hunk ↗ jump to hunk
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)