42 lines
1.3 KiB
Diff
42 lines
1.3 KiB
Diff
From 8fbce6094dc3acad11c464723d97d3215951c5d4 Mon Sep 17 00:00:00 2001
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From: liaichun <liaichun@huawei.com>
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Date: Mon, 20 Apr 2020 15:26:17 +0800
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Subject: [PATCH] dnsmasq-2.77-underflow
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---
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src/forward.c | 3 +++
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src/rfc1035.c | 3 +++
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2 files changed, 6 insertions(+)
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diff --git a/src/forward.c b/src/forward.c
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index fde554d..47ccd91 100644
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--- a/src/forward.c
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+++ b/src/forward.c
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@@ -1546,6 +1546,9 @@ void receive_query(struct listener *listen, time_t now)
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else if (udp_size < PACKETSZ)
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udp_size = PACKETSZ; /* Sanity check - can't reduce below default. RFC 6891 6.2.3 */
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}
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+ // Make sure the udp size is not smaller than the incoming message so that we
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+ // do not underflow
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+ if (udp_size < n) udp_size = n;
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#ifdef HAVE_AUTH
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if (auth_dns)
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diff --git a/src/rfc1035.c b/src/rfc1035.c
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index fefe63d..6253794 100644
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--- a/src/rfc1035.c
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+++ b/src/rfc1035.c
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@@ -1340,6 +1340,9 @@ size_t answer_request(struct dns_header *header, char *limit, size_t qlen,
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size_t len;
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int rd_bit = (header->hb3 & HB3_RD);
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+ // Make sure we do not underflow here too.
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+ if (qlen > (limit - ((char *)header))) return 0;
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+
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/* never answer queries with RD unset, to avoid cache snooping. */
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if (ntohs(header->ancount) != 0 ||
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ntohs(header->nscount) != 0 ||
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--
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2.23.0
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