From: Roberto Sassu
> Sent: 27 April 2020 13:51
...
> > > -static inline unsigned long ima_hash_key(u8 *digest)
> > > +static inline unsigned int ima_hash_key(u8 *digest)
> > > {
> > > - return hash_long(*digest, IMA_HASH_BITS);
> > > + return (*(unsigned int *)digest % IMA_MEASURE_HTABLE_SIZE);
> >
> > That almost certainly isn't right.
> > It falls foul of the *(integer_type *)ptr being almost always wrong.
>
> I didn't find the problem. Can you please explain?
The general problem with *(int_type *)ptr is that it does completely
the wrong thing if 'ptr' is the address of a larger integer type on
a big-endian system.
You may also get a misaligned access trap.
In this case I guess that digest is actually u8[SHA1_DIGEST_SIZE].
Maybe what you should return is:
(digest[0] | digest[1] << 8) % IMA_MEASURE_HTABLE_SIZE;
and comment that there is no point taking a hash of part of
a SHA1 digest.
David
-
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