commit 3b1f7f75a7efa51ae5549a6413e90066cfe307a8 Author: Nick Mathewson nickm@torproject.org Date: Sat Apr 19 13:16:56 2014 -0400

scan-build: memarea_strndup() undefined behavior

The memarea_strndup() function would have hit undefined behavior by creating an 'end' pointer off the end of a string if it had ever been given an 'n' argument bigger than the length of the memory ares that it's scanning. Fortunately, we never did that except in the unit tests. But it's not a safe behavior to leave lying around. --- src/common/memarea.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-)

diff --git a/src/common/memarea.c b/src/common/memarea.c index e2d07fc..bcaea09 100644 --- a/src/common/memarea.c +++ b/src/common/memarea.c @@ -291,14 +291,11 @@ memarea_strdup(memarea_t *area, const char *s) char * memarea_strndup(memarea_t *area, const char *s, size_t n) { - size_t ln; + size_t ln = 0; char *result; - const char *cp, *end = s+n; tor_assert(n < SIZE_T_CEILING); - for (cp = s; cp < end && *cp; ++cp) + for (ln = 0; ln < n && s[ln]; ++ln) ; - /* cp now points to s+n, or to the 0 in the string. */ - ln = cp-s; result = memarea_alloc(area, ln+1); memcpy(result, s, ln); result[ln]='\0';