From: David Howells <dhowells@redhat.com>
To: keyrings@vger.kernel.org
Cc: David Woodhouse <David.Woodhouse@intel.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
dhowells@redhat.com, linux-security-module@vger.kernel.org,
Rudolf Polzer <rpolzer@google.com>
Subject: [RFC PATCH 1/4] X.509: Fix leap year handling again
Date: Mon, 04 Jan 2016 22:17:05 +0000 [thread overview]
Message-ID: <20160104221705.19818.67138.stgit@warthog.procyon.org.uk> (raw)
In-Reply-To: <20160104221658.19818.56223.stgit@warthog.procyon.org.uk>
There are still a couple of minor issues in the X.509 leap year handling:
(1) To avoid doing a modulus-by-400 in addition to a modulus-by-100 when
determining whether the year is a leap year or not, I divided the year
by 100 after doing the modulus-by-100, thereby letting the compiler do
one instruction for both, and then did a modulus-by-4.
Unfortunately, I then passed the now-modified year value to mktime64()
to construct a time value.
Since this isn't a fast path and since mktime64() does a bunch of
divisions, just condense down to "% 400". It's also easier to read.
(2) The default month length for any February where the year doesn't
divide by four exactly is obtained from the month_length[] array where
the value is 29, not 28.
This is fixed by altering the table.
Reported-by: Rudolf Polzer <rpolzer@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Acked-By: David Woodhouse <David.Woodhouse@intel.com>
cc: stable@vger.kernel.org
---
crypto/asymmetric_keys/x509_cert_parser.c | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/crypto/asymmetric_keys/x509_cert_parser.c b/crypto/asymmetric_keys/x509_cert_parser.c
index 021d39c0ba75..13c4e5a5fe8c 100644
--- a/crypto/asymmetric_keys/x509_cert_parser.c
+++ b/crypto/asymmetric_keys/x509_cert_parser.c
@@ -494,7 +494,7 @@ int x509_decode_time(time64_t *_t, size_t hdrlen,
unsigned char tag,
const unsigned char *value, size_t vlen)
{
- static const unsigned char month_lengths[] = { 31, 29, 31, 30, 31, 30,
+ static const unsigned char month_lengths[] = { 31, 28, 31, 30, 31, 30,
31, 31, 30, 31, 30, 31 };
const unsigned char *p = value;
unsigned year, mon, day, hour, min, sec, mon_len;
@@ -540,9 +540,9 @@ int x509_decode_time(time64_t *_t, size_t hdrlen,
if (year % 4 == 0) {
mon_len = 29;
if (year % 100 == 0) {
- year /= 100;
- if (year % 4 != 0)
- mon_len = 28;
+ mon_len = 28;
+ if (year % 400 == 0)
+ mon_len = 29;
}
}
}
next prev parent reply other threads:[~2016-01-04 22:17 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-01-04 22:16 [PATCH 0/4] X.509: Fix time handling David Howells
2016-01-04 22:17 ` David Howells [this message]
2016-01-20 15:12 ` [RFC PATCH 1/4] X.509: Fix leap year handling again Rudolf Polzer
2016-01-20 15:18 ` David Howells
2016-01-04 22:17 ` [RFC PATCH 2/4] Handle ISO 8601 leap seconds and encodings of midnight in mktime64() David Howells
2016-01-04 22:17 ` [RFC PATCH 3/4] X.509: Support leap seconds David Howells
2016-01-20 15:08 ` Rudolf Polzer
2016-01-04 22:17 ` [RFC PATCH 4/4] X.509: Handle midnight alternative notation in GeneralizedTime David Howells
2016-01-20 15:08 ` Rudolf Polzer
2016-01-20 15:20 ` David Howells
2016-01-20 15:30 ` One Thousand Gnomes
2016-02-03 16:25 ` David Howells
2016-02-03 16:28 ` David Howells
2016-02-04 17:38 ` One Thousand Gnomes
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