From 9b132e556774c744f9052581d2d8d0fab417e97c Mon Sep 17 00:00:00 2001 From: Alexey Izbyshev Date: Sun, 29 Jan 2023 19:46:51 +0300 Subject: prevent CNAME/PTR parsing from reading data past the response end DNS parsing callbacks pass the response buffer end instead of the actual response end to dn_expand, so a malformed DNS response can use message compression to make dn_expand jump past the response end and attempt to parse uninitialized parts of that buffer, which might succeed and return garbage. --- src/network/getnameinfo.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'src/network/getnameinfo.c') diff --git a/src/network/getnameinfo.c b/src/network/getnameinfo.c index 949e1811..080d3c06 100644 --- a/src/network/getnameinfo.c +++ b/src/network/getnameinfo.c @@ -108,10 +108,10 @@ static void reverse_services(char *buf, int port, int dgram) __fclose_ca(f); } -static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet) +static int dns_parse_callback(void *c, int rr, const void *data, int len, const void *packet, int plen) { if (rr != RR_PTR) return 0; - if (__dn_expand(packet, (const unsigned char *)packet + 512, + if (__dn_expand(packet, (const unsigned char *)packet + plen, data, c, 256) <= 0) *(char *)c = 0; return 0; -- cgit v1.2.1