From 5c281d182ecdd0a424b64f7698f32467f8f67b71 Mon Sep 17 00:00:00 2001 From: Jukka Rissanen Date: Wed, 9 Aug 2017 10:16:46 +0300 Subject: dnsproxy: Fix crash on malformed DNS response If the response query string is malformed, we might access memory pass the end of "name" variable in parse_response(). CVE: CVE-2017-12865 Upstream-Status: Backport [https://git.kernel.org/pub/scm/network/connman/connman.git/patch/?id=5c281d182ecdd0a424b64f7698f32467f8f67b71] Signed-off-by: Sona Sarmadi --- src/dnsproxy.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/src/dnsproxy.c b/src/dnsproxy.c index 38ac5bf..40b4f15 100644 --- a/src/dnsproxy.c +++ b/src/dnsproxy.c @@ -838,7 +838,7 @@ static struct cache_entry *cache_check(gpointer request, int *qtype, int proto) static int get_name(int counter, unsigned char *pkt, unsigned char *start, unsigned char *max, unsigned char *output, int output_max, int *output_len, - unsigned char **end, char *name, int *name_len) + unsigned char **end, char *name, size_t max_name, int *name_len) { unsigned char *p; @@ -859,7 +859,7 @@ static int get_name(int counter, return get_name(counter + 1, pkt, pkt + offset, max, output, output_max, output_len, end, - name, name_len); + name, max_name, name_len); } else { unsigned label_len = *p; @@ -869,6 +869,9 @@ static int get_name(int counter, if (*output_len > output_max) return -ENOBUFS; + if ((*name_len + 1 + label_len + 1) > max_name) + return -ENOBUFS; + /* * We need the original name in order to check * if this answer is the correct one. @@ -900,14 +903,14 @@ static int parse_rr(unsigned char *buf, unsigned char *start, unsigned char *response, unsigned int *response_size, uint16_t *type, uint16_t *class, int *ttl, int *rdlen, unsigned char **end, - char *name) + char *name, size_t max_name) { struct domain_rr *rr; int err, offset; int name_len = 0, output_len = 0, max_rsp = *response_size; err = get_name(0, buf, start, max, response, max_rsp, - &output_len, end, name, &name_len); + &output_len, end, name, max_name, &name_len); if (err < 0) return err; @@ -1033,7 +1036,8 @@ static int parse_response(unsigned char *buf, int buflen, memset(rsp, 0, sizeof(rsp)); ret = parse_rr(buf, ptr, buf + buflen, rsp, &rsp_len, - type, class, ttl, &rdlen, &next, name); + type, class, ttl, &rdlen, &next, name, + sizeof(name) - 1); if (ret != 0) { err = ret; goto out; @@ -1099,7 +1103,7 @@ static int parse_response(unsigned char *buf, int buflen, */ ret = get_name(0, buf, next - rdlen, buf + buflen, rsp, rsp_len, &output_len, &end, - name, &name_len); + name, sizeof(name) - 1, &name_len); if (ret != 0) { /* just ignore the error at this point */ ptr = next; -- cgit v1.1