From: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
To: musl@lists.openwall.com
Cc: Alexey Kodanev <aleksei.kodanev@bell-sw.com>
Subject: [musl] [PATCH v2] dns: check length field in tcp response message
Date: Wed, 22 Mar 2023 17:48:40 +0300 [thread overview]
Message-ID: <20230322144840.138539-1-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 'alens[i]', it will result
in an out-of-bounds reading in __dns_parse().
To fix this, limit the length to the size of the received buffer.
---
v2: move the check to name_from_dns()
src/network/lookup_name.c | 1 +
1 file changed, 1 insertion(+)
diff --git a/src/network/lookup_name.c b/src/network/lookup_name.c
index 5f6867cb..e324f39d 100644
--- a/src/network/lookup_name.c
+++ b/src/network/lookup_name.c
@@ -179,6 +179,7 @@ static int name_from_dns(struct address buf[static MAXADDRS], char canon[static
for (i=nq-1; i>=0; i--) {
ctx.rrtype = qtypes[i];
+ if (alens[i] > sizeof(abuf[i])) alens[i] = sizeof(abuf[i]);
__dns_parse(abuf[i], alens[i], dns_parse_callback, &ctx);
}
--
2.25.1
reply other threads:[~2023-03-22 14:49 UTC|newest]
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