Merge branch 'rs/apply-fuzzy-match-fix' into maint

A fix for an ancient bug in "git apply --ignore-space-change" codepath.

* rs/apply-fuzzy-match-fix:
apply: avoid out-of-bounds access in fuzzy_matchlines()

diff --git a/apply.c b/apply.c
index c022af53a24bf56556d136a3456862cf6a2ca7cc..d4c1dd7efd3422ec8f6a08ecaae29dee15d775d7 100644 (file)
--- a/apply.c
+++ b/apply.c
@@ -305,52 +305,33 @@ static uint32_t hash_line(const char *cp, size_t len)
 static int fuzzy_matchlines(const char *s1, size_t n1,
                            const char *s2, size_t n2)
 {
-       const char *last1 = s1 + n1 - 1;
-       const char *last2 = s2 + n2 - 1;
-       int result = 0;
+       const char *end1 = s1 + n1;
+       const char *end2 = s2 + n2;
 
        /* ignore line endings */
-       while ((*last1 == '\r') || (*last1 == '\n'))
-               last1--;
-       while ((*last2 == '\r') || (*last2 == '\n'))
-               last2--;
-
-       /* skip leading whitespaces, if both begin with whitespace */
-       if (s1 <= last1 && s2 <= last2 && isspace(*s1) && isspace(*s2)) {
-               while (isspace(*s1) && (s1 <= last1))
-                       s1++;
-               while (isspace(*s2) && (s2 <= last2))
-                       s2++;
-       }
-       /* early return if both lines are empty */
-       if ((s1 > last1) && (s2 > last2))
-               return 1;
-       while (!result) {
-               result = *s1++ - *s2++;
-               /*
-                * Skip whitespace inside. We check for whitespace on
-                * both buffers because we don't want "a b" to match
-                * "ab"
-                */
-               if (isspace(*s1) && isspace(*s2)) {
-                       while (isspace(*s1) && s1 <= last1)
+       while (s1 < end1 && (end1[-1] == '\r' || end1[-1] == '\n'))
+               end1--;
+       while (s2 < end2 && (end2[-1] == '\r' || end2[-1] == '\n'))
+               end2--;
+
+       while (s1 < end1 && s2 < end2) {
+               if (isspace(*s1)) {
+                       /*
+                        * Skip whitespace. We check on both buffers
+                        * because we don't want "a b" to match "ab".
+                        */
+                       if (!isspace(*s2))
+                               return 0;
+                       while (s1 < end1 && isspace(*s1))
                                s1++;
-                       while (isspace(*s2) && s2 <= last2)
+                       while (s2 < end2 && isspace(*s2))
                                s2++;
-               }
-               /*
-                * If we reached the end on one side only,
-                * lines don't match
-                */
-               if (
-                   ((s2 > last2) && (s1 <= last1)) ||
-                   ((s1 > last1) && (s2 <= last2)))
+               } else if (*s1++ != *s2++)
                        return 0;
-               if ((s1 > last1) && (s2 > last2))
-                       break;
        }
 
-       return !result;
+       /* If we reached the end on one side only, lines don't match. */
+       return s1 == end1 && s2 == end2;
 }
 
 static void add_line_info(struct image *img, const char *bol, size_t len, unsigned flag)