-----Original Message----- From: David Laight [mailto:David.Laight@ACULAB.COM] Sent: Monday, April 27, 2020 4:28 PM To: Roberto Sassu roberto.sassu@huawei.com; zohar@linux.ibm.com; rgoldwyn@suse.de Cc: linux-integrity@vger.kernel.org; linux-security-module@vger.kernel.org; linux-kernel@vger.kernel.org; Silviu Vlasceanu Silviu.Vlasceanu@huawei.com; Krzysztof Struczynski krzysztof.struczynski@huawei.com; stable@vger.kernel.org Subject: RE: [PATCH v2 3/6] ima: Fix ima digest hash table key calculation
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.
Ok, thanks.
Roberto
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David
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