diff mbox series

[v4,1/7] parse: fix off-by-one for minimum signed values

Message ID 20250417-b4-pks-parse-options-integers-v4-1-9cbc76b61cfe@pks.im (mailing list archive)
State Accepted
Commit 8f282bdff0b49744b45d619075b59a5e8b596613
Headers show
Series parse-options: harden handling of integer values | expand

Commit Message

Patrick Steinhardt April 17, 2025, 10:49 a.m. UTC 
We accept a maximum value in `git_parse_signed()` that restricts the
range of accepted integers. As the intent is to pass `INT*_MAX` values
here, this maximum doesn't only act as the upper bound, but also as the
implicit lower bound of the accepted range.

This lower bound is calculated by negating the maximum. But given that
the maximum value of a signed integer with N bits is `2^(N-1)-1` whereas
the minimum value is `-2^(N-1)` we have an off-by-one error in the lower
bound.

Fix this off-by-one error by using `-max - 1` as lower bound instead.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 parse.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/parse.c b/parse.c
index 7a60a4f816c..3c47448ca67 100644
--- a/parse.c
+++ b/parse.c
@@ -38,7 +38,7 @@  int git_parse_signed(const char *value, intmax_t *ret, intmax_t max)
 			errno = EINVAL;
 			return 0;
 		}
-		if ((val < 0 && -max / factor > val) ||
+		if ((val < 0 && (-max - 1) / factor > val) ||
 		    (val > 0 && max / factor < val)) {
 			errno = ERANGE;
 			return 0;