From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Subject: [PATCH 1/5] X.509: Fix leap year handling again From: David Howells To: keyrings@vger.kernel.org Cc: David Woodhouse , linux-kernel@vger.kernel.org, stable@vger.kernel.org, dhowells@redhat.com, linux-security-module@vger.kernel.org, Rudolf Polzer Date: Fri, 18 Dec 2015 00:01:55 +0000 Message-ID: <20151218000155.29483.78145.stgit@warthog.procyon.org.uk> In-Reply-To: <20151218000148.29483.67155.stgit@warthog.procyon.org.uk> References: <20151218000148.29483.67155.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: 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 Signed-off-by: David Howells Acked-By: David Woodhouse 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; } } }