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src/mjson.c: using alloca in a loop can lead to a stack overflow #63

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src/mjson.c: using alloca in a loop can lead to a stack overflow #63

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6 changes: 4 additions & 2 deletions src/mjson.c
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Original file line number Diff line number Diff line change
Expand Up @@ -821,7 +821,7 @@ int mjson_merge(const char *s, int n, const char *s2, int n2,
if (n < 2) return len;
len += fn("{", 1, userdata);
while ((off = mjson_next(s, n, off, &koff, &klen, &voff, &vlen, &t)) != 0) {
char *path = (char *) alloca((size_t) klen + 1);
char *path = (char *) malloc((size_t) klen + 1);
const char *val;
memcpy(path, "$.", 2);
memcpy(path + 2, s + koff + 1, (size_t) (klen - 2));
Expand All @@ -841,11 +841,12 @@ int mjson_merge(const char *s, int n, const char *s2, int n2,
len += fn(val, vlen, userdata);
}
comma = 1;
free(path);
}
// Add missing keys
off = 0;
while ((off = mjson_next(s2, n2, off, &koff, &klen, &voff, &vlen, &t)) != 0) {
char *path = (char *) alloca((size_t) klen + 1);
char *path = (char *) malloc((size_t) klen + 1);
const char *val;
if (t == MJSON_TOK_NULL) continue;
memcpy(path, "$.", 2);
Expand All @@ -857,6 +858,7 @@ int mjson_merge(const char *s, int n, const char *s2, int n2,
len += fn(":", 1, userdata);
len += fn(s2 + voff, vlen, userdata);
comma = 1;
free(path);
}
len += fn("}", 1, userdata);
return len;
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