From 1dca155fe3fac29e847d2d8ff1087d892a129a9c Mon Sep 17 00:00:00 2001 From: Jeff King Date: Mon, 24 Feb 2014 02:46:37 -0500 Subject: [PATCH] log: handle integer overflow in timestamps If an ident line has a ridiculous date value like (2^64)+1, we currently just pass ULONG_MAX along to the date code, which can produce nonsensical dates. On systems with a signed long time_t (e.g., 64-bit glibc systems), this actually doesn't end up too bad. The ULONG_MAX is converted to -1, we apply the timezone field to that, and the result ends up somewhere between Dec 31, 1969 and Jan 1, 1970. However, there is still a few good reasons to detect the overflow explicitly: 1. On systems where "unsigned long" is smaller than time_t, we get a nonsensical date in the future. 2. Even where it would produce "Dec 31, 1969", it's easier to recognize "midnight Jan 1" as a consistent sentinel value for "we could not parse this". 3. Values which do not overflow strtoul but do overflow a signed time_t produce nonsensical values in the past. For example, on a 64-bit system with a signed long time_t, a timestamp of 18446744073000000000 produces a date in 1947. We also recognize overflow in the timezone field, which could produce nonsensical results. In this case we show the parsed date, but in UTC. Signed-off-by: Jeff King Signed-off-by: Junio C Hamano --- pretty.c | 10 ++++++++-- t/t4212-log-corrupt.sh | 16 ++++++++++++++++ 2 files changed, 24 insertions(+), 2 deletions(-) diff --git a/pretty.c b/pretty.c index acbfceb5fe..4da9a682f3 100644 --- a/pretty.c +++ b/pretty.c @@ -401,8 +401,14 @@ static const char *show_ident_date(const struct ident_split *ident, if (ident->date_begin && ident->date_end) date = strtoul(ident->date_begin, NULL, 10); - if (ident->tz_begin && ident->tz_end) - tz = strtol(ident->tz_begin, NULL, 10); + if (date_overflows(date)) + date = 0; + else { + if (ident->tz_begin && ident->tz_end) + tz = strtol(ident->tz_begin, NULL, 10); + if (tz == LONG_MAX || tz == LONG_MIN) + tz = 0; + } return show_date(date, tz, mode); } diff --git a/t/t4212-log-corrupt.sh b/t/t4212-log-corrupt.sh index 611b687a3c..80542d624b 100755 --- a/t/t4212-log-corrupt.sh +++ b/t/t4212-log-corrupt.sh @@ -60,4 +60,20 @@ test_expect_success 'unparsable dates produce sentinel value (%ad)' ' test_cmp expect actual ' +# date is 2^64 + 1 +test_expect_success 'date parser recognizes integer overflow' ' + commit=$(munge_author_date HEAD 18446744073709551617) && + echo "Thu Jan 1 00:00:00 1970 +0000" >expect && + git log -1 --format=%ad $commit >actual && + test_cmp expect actual +' + +# date is 2^64 - 2 +test_expect_success 'date parser recognizes time_t overflow' ' + commit=$(munge_author_date HEAD 18446744073709551614) && + echo "Thu Jan 1 00:00:00 1970 +0000" >expect && + git log -1 --format=%ad $commit >actual && + test_cmp expect actual +' + test_done -- 2.11.4.GIT