From 604f8a6c4d58a646c8722fdf7cad9ee67479d8f7 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Mon, 31 Jan 2022 10:20:21 -0800
Subject: [PATCH] dd: do not access uninitialized
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* src/dd.c (parse_integer): Avoid undefined behavior
that accesses an uninitialized ‘n’ when e == LONGINT_INVALID.
Return more-accurate error code when INTMAX_MAX < n.
---
 src/dd.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/dd.c b/src/dd.c
index e55f87f149..7360a49738 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -1427,8 +1427,10 @@ static intmax_t
 parse_integer (char const *str, strtol_error *invalid)
 {
   /* Call xstrtoumax, not xstrtoimax, since we don't want to
-     allow strings like "  -0".  */
-  uintmax_t n;
+     allow strings like " -0".  Initialize N to an interminate value;
+     calling code should not rely on this function returning 0
+     when *INVALID represents a non-overflow error.  */
+  uintmax_t n = 0;
   char *suffix;
   strtol_error e = xstrtoumax (str, &suffix, 10, &n, "bcEGkKMPTwYZ0");
 
@@ -1468,7 +1470,7 @@ parse_integer (char const *str, strtol_error *invalid)
 
   if (INTMAX_MAX < n)
     {
-      *invalid = LONGINT_OVERFLOW;
+      *invalid = e | LONGINT_OVERFLOW;
       return INTMAX_MAX;
     }