From 61ee4578f59e4478bf76fa584b199e1a22521cb0 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sun, 7 Jan 2024 16:09:49 -0800
Subject: [PATCH] * src/arscan.c (parse_int): Fix integer overflow test
Use intprops.h macros rather than trying to detect integer overflow by
hand, and doing it incorrectly. Example of incorrect behavior:
if val == 3689348814741910323, base == 10, UINTMAX_WIDTH == 64, and
*ptr == '0' then (val*base)+(*ptr-'0') yields 18446744073709551614
which is greater than val even though overflow has occurred.
Fortunately this bug could not be triggered on GNU/Linux hosts,
although it may be possible on platforms (if any) where struct ar_hdr
has members so large that they can represent integers that do not fit
int uintmax_t.
---
src/arscan.c | 12 ++++--------
1 file changed, 4 insertions(+), 8 deletions(-)
diff --git a/src/arscan.c b/src/arscan.c
index eed90c80..f86e95f7 100644
--- a/src/arscan.c
+++ b/src/arscan.c
@@ -395,16 +395,12 @@ parse_int (const char *ptr, const size_t len, const int base, uintmax_t max,
while (ptr < ep && *ptr != ' ')
{
- uintmax_t nv;
-
- if (*ptr < '0' || *ptr > maxchar)
+ if (*ptr < '0' || *ptr > maxchar
+ || INT_MULTIPLY_WRAPV (val, base, &val)
+ || INT_ADD_WRAPV (val, *ptr - '0', &val)
+ || val > max)
OSSS (fatal, NILF,
_("invalid %s for archive %s member %s"), type, archive, name);
- nv = (val * base) + (*ptr - '0');
- if (nv < val || nv > max)
- OSSS (fatal, NILF,
- _("invalid %s for archive %s member %s"), type, archive, name);
- val = nv;
++ptr;
}