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dm crypt: fix benbi IV constructor crash if used in authenticated mode

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If benbi IV is used in AEAD construction, for example:
  cryptsetup luksFormat <device> --cipher twofish-xts-benbi --key-size 512 --integrity=hmac-sha256
the constructor uses wrong skcipher function and crashes:

 BUG: kernel NULL pointer dereference, address: 00000014
 ...
 EIP: crypt_iv_benbi_ctr+0x15/0x70 [dm_crypt]
 Call Trace:
  ? crypt_subkey_size+0x20/0x20 [dm_crypt]
  crypt_ctr+0x567/0xfc0 [dm_crypt]
  dm_table_add_target+0x15f/0x340 [dm_mod]

Fix this by properly using crypt_aead_blocksize() in this case.

Fixes: ef43aa3806 ("dm crypt: add cryptographic data integrity protection (authenticated encryption)")
Cc: stable@vger.kernel.org # v4.12+
Link: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=941051
Reported-by: Jerad Simpson <jbsimpson@gmail.com>
Signed-off-by: Milan Broz <gmazyland@gmail.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
This commit is contained in:
Milan Broz 2020-01-06 10:11:47 +01:00 committed by Mike Snitzer
parent bbb1658461
commit 4ea9471fbd
1 changed files with 8 additions and 2 deletions
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10
drivers/md/dm-crypt.c
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@ -343,8 +343,14 @@ static int crypt_iv_essiv_gen(struct crypt_config *cc, u8 *iv,
static int crypt_iv_benbi_ctr(struct crypt_config *cc, struct dm_target *ti,
const char *opts)
{
unsigned bs = crypto_skcipher_blocksize(any_tfm(cc));
int log = ilog2(bs);
unsigned bs;
int log;
if (test_bit(CRYPT_MODE_INTEGRITY_AEAD, &cc->cipher_flags))
bs = crypto_aead_blocksize(any_tfm_aead(cc));
else
bs = crypto_skcipher_blocksize(any_tfm(cc));
log = ilog2(bs);
/* we need to calculate how far we must shift the sector count
* to get the cipher block count, we use this shift in _gen */