36 lines
1.2 KiB
Diff
36 lines
1.2 KiB
Diff
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From 45ca5d3fcb6f874bf5ba55d0e9651cef68515395 Mon Sep 17 00:00:00 2001
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From: Rich Felker <dalias@aerifal.cx>
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Date: Wed, 18 Oct 2017 14:50:03 -0400
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Subject: [PATCH] in dns parsing callback, enforce MAXADDRS to preclude
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overflow
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MAXADDRS was chosen not to need enforcement, but the logic used to
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compute it assumes the answers received match the RR types of the
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queries. specifically, it assumes that only one replu contains A
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record answers. if the replies to both the A and the AAAA query have
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their answer sections filled with A records, MAXADDRS can be exceeded
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and clobber the stack of the calling function.
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this bug was found and reported by Felix Wilhelm.
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Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
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---
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src/network/lookup_name.c | 1 +
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1 file changed, 1 insertion(+)
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diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
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index 066be4d5..209c20f0 100644
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--- a/src/network/lookup_name.c
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+++ b/src/network/lookup_name.c
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@@ -111,6 +111,7 @@ static int dns_parse_callback(void *c, int rr, const void *data, int len, const
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{
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char tmp[256];
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struct dpc_ctx *ctx = c;
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+ if (ctx->cnt >= MAXADDRS) return -1;
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switch (rr) {
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case RR_A:
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if (len != 4) return -1;
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--
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2.11.0
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