From: Johannes Schindelin via GitGitGadget Date: Wed, 14 Oct 2026 06:09:31 GMT Subject: [PATCH 5/5] date: avoid overflow in approxidate relative-time multiplication Message-ID: In-Reply-To: From: Johannes Schindelin The `approxidate_alpha()` function multiplies a time unit length (e.g., 604800 for weeks) by a user-supplied number to compute a time offset in seconds. Both operands are `int`, and the product is passed to `update_tm()` as `time_t`. For inputs like "99999 weeks ago", the int multiplication overflows (604800 * 99999 is roughly 60 billion, far beyond `INT_MAX`), producing a wrapped value that results in a wrong date. Use the checked `time_t` multiplication so oversized products do not overflow or wrap around. On platforms where `time_t` is unsigned (and where the pre-processor allows us to determine this fact), reject counts that are too large and report a parse error. Narrowing them first could otherwise produce negative or truncated values that become bogus offsets. Leave signed `time_t` count parsing unchanged. Pointed out by Coverity. Assisted-by: Claude Opus 4.6 and GPT-6.1 Sol Signed-off-by: Johannes Schindelin --- date.c | 26 ++++++++++++++++++++++++-- 1 file changed, 24 insertions(+), 2 deletions(-) diff --git a/date.c b/date.c index 014065b419..0d65804d2f 100644 --- a/date.c +++ b/date.c @@ -1298,7 +1298,18 @@ static const char *approxidate_alpha(const char *date, struct tm *tm, struct tm while (tl->type) { size_t len = strlen(tl->type); if (match_string(date, tl->type) >= len-1) { - update_tm(tm, now, tl->length * *num); + time_t length = tl->length, num_t = *num; + time_t seconds; +#ifndef is_unsigned_type + seconds = length * num_t; +#else + time_t max_val = is_unsigned_type(length) + ? maximum_unsigned_value_of_type(length) + : maximum_signed_value_of_type(length); + seconds = mult_overflows(length, num_t) + ? max_val : length * num_t; +#endif + update_tm(tm, now, seconds); *num = 0; *touched = 1; return end; @@ -1368,8 +1379,15 @@ static const char *approxidate_digit(const char *date, struct tm *tm, int *num, } /* Accept zero-padding only for small numbers ("Dec 02", never "Dec 0002") */ - if (date[0] != '0' || end - date <= 2) + if (date[0] != '0' || end - date <= 2) { +#ifdef is_unsigned_type + if (is_unsigned_type((time_t)0) && + (number > INT_MAX || + number > maximum_unsigned_value_of_type((time_t)0))) + return NULL; +#endif *num = number; + } return end; } @@ -1398,6 +1416,10 @@ static timestamp_t approxidate_str(const char *date, if (isdigit(c)) { pending_number(&tm, &number); date = approxidate_digit(date-1, &tm, &number, time_sec); + if (!date) { + *error_ret = 1; + return 0; + } touched = 1; continue; } -- gitgitgadget