Messages in this thread | | | Date | Tue, 8 Nov 2022 15:51:51 +0100 | Subject | Re: [dm-devel] [PATCH] dm-crypt: fix incorrect use of strcmp when telling if there is no key | From | Milan Broz <> |
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On 11/7/22 13:22, Coiby Xu wrote: > strcmp returns 0 when two strings are equal. > > Fixes: 69a8cfcda210 ("dm crypt: set key size early") > Signed-off-by: Coiby Xu <coxu@redhat.com> > --- > drivers/md/dm-crypt.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/drivers/md/dm-crypt.c b/drivers/md/dm-crypt.c > index 159c6806c19b..cfefe0f18150 100644 > --- a/drivers/md/dm-crypt.c > +++ b/drivers/md/dm-crypt.c > @@ -2590,7 +2590,7 @@ static int crypt_set_key(struct crypt_config *cc, char *key) > int key_string_len = strlen(key); > > /* Hyphen (which gives a key_size of zero) means there is no key. */ > - if (!cc->key_size && strcmp(key, "-")) > + if (!cc->key_size && !strcmp(key, "-")) > goto out;
NACK. The code is correct.
The comment is a little bit misleading - it actually says that "-" is valid here.
If key_size is 0 (see above: key_size = strlen(key) >> 1;) and key is NOT "-" (empty key) return error.
Key "-" is a valid key, means no key used (used for null cipher).
Try this with and without your patch (it uses null cipher that takes no key):
dmsetup create test --table "0 8 crypt cipher_null-ecb - 0 /dev/sdb 0"
With your patch it no longer works.
Please, run cryptsetup testsuite before sending patches, tests/mode-tests fails immediately with your patch!
Thanks, Milan
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