diff options
| -rw-r--r-- | ChangeLog | 2 | ||||
| -rw-r--r-- | src/or/eventdns.c | 5 |
2 files changed, 7 insertions, 0 deletions
@@ -27,6 +27,8 @@ Changes in version 0.1.2.7-alpha - 2007-??-?? - If our system clock jumps back in time, don't publish a negative uptime in the descriptor. Also, don't let the global rate limiting buckets go absurdly negative. + - Detect and reject malformed DNS responses containing circular + pointer loops. o Minor bugfixes: - When computing clock skew from directory HTTP headers, consider what diff --git a/src/or/eventdns.c b/src/or/eventdns.c index 35efbff00a..e123592e01 100644 --- a/src/or/eventdns.c +++ b/src/or/eventdns.c @@ -736,6 +736,7 @@ static inline int name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { int name_end = -1; int j = *idx; + int ptr_count = 0; #define GET32(x) do { if (j + 4 > length) goto err; memcpy(&_t32, packet + j, 4); j += 4; x = ntohl(_t32); } while(0); #define GET16(x) do { if (j + 2 > length) goto err; memcpy(&_t, packet + j, 2); j += 2; x = ntohs(_t); } while(0); #define GET8(x) do { if (j >= length) goto err; x = packet[j++]; } while(0); @@ -759,7 +760,11 @@ name_parse(u8 *packet, int length, int *idx, char *name_out, int name_out_len) { GET8(ptr_low); if (name_end < 0) name_end = j; j = (((int)label_len & 0x3f) << 8) + ptr_low; + /* Make sure that the target offset is in-bounds. */ if (j < 0 || j >= length) return -1; + /* If we've jumped more times than there are characters in the + * message, we must have a loop. */ + if (++ptr_count > length) return -1; continue; } if (label_len > 63) return -1; |