From: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
To: musl@lists.openwall.com
Cc: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
Subject: [musl] [PATCH] dns: check length field in tcp response message
Date: Wed, 22 Mar 2023 15:29:16 +0300 [thread overview]
Message-ID: <20230322122916.116088-1-aleksei.kodanev@bell-sw.com> (raw)
The received length field in the message may be greater than the
size of the 'answer' buffer in which the message resides. Currently,
ABUF_SIZE is 768. And if we get a larger 'alen', it will result
in an out-of-bounds reading during parsing, because 'alen' will
be passed to __dns_parse() later:
__dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
To fix this, limit 'alen' to the size of the received buffer.
---
src/network/res_msend.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/network/res_msend.c b/src/network/res_msend.c
index fef7e3a2..291853de 100644
--- a/src/network/res_msend.c
+++ b/src/network/res_msend.c
@@ -297,6 +297,7 @@ int __res_msend_rc(int nqueries, const unsigned char *const *queries,
int rcode = answers[i][3] & 15;
if (rcode != 0 && rcode != 3)
goto out;
+ if (alen > asize) alen = asize;
/* Storing the length here commits the accepted answer.
* Immediately close TCP socket so as not to consume
--
2.25.1
next reply other threads:[~2023-03-22 12:30 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-03-22 12:29 Alexey Kodanev [this message]
2023-03-22 13:16 ` Rich Felker
2023-03-22 13:48 ` Alexey Kodanev
2023-03-22 14:07 ` Rich Felker
2023-05-08 16:25 ` Alexey Izbyshev
2024-02-29 10:49 ` Alexey Izbyshev
2024-02-29 15:36 ` Rich Felker
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