87 lines
3.5 KiB
Diff
87 lines
3.5 KiB
Diff
From: Debian Qt/KDE Maintainers <debian-qt-kde@lists.debian.org>
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Date: Mon, 20 Nov 2023 01:57:45 +0000
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Subject: QDnsLookup/Unix: make sure we don't overflow the buffer
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Origin: upstream, https://code.qt.io/cgit/qt/qtbase.git/commit/?id=7dba2c87619d558a
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Last-Update: 2023-05-25
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The DNS Records are variable length and encode their size in 16 bits
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before the Record Data (RDATA). Ensure that both the RDATA and the
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Record header fields before it fall inside the buffer we have.
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Additionally reject any replies containing more than one query records.
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---
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src/network/kernel/qdnslookup_unix.cpp | 31 +++++++++++++++++++++++++------
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1 file changed, 25 insertions(+), 6 deletions(-)
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diff --git a/src/network/kernel/qdnslookup_unix.cpp b/src/network/kernel/qdnslookup_unix.cpp
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index 12b40fc..99e999d 100644
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--- a/src/network/kernel/qdnslookup_unix.cpp
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+++ b/src/network/kernel/qdnslookup_unix.cpp
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@@ -227,7 +227,6 @@ void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestN
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// responseLength in case of error, we still can extract the
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// exact error code from the response.
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HEADER *header = (HEADER*)response;
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- const int answerCount = ntohs(header->ancount);
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switch (header->rcode) {
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case NOERROR:
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break;
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@@ -260,18 +259,31 @@ void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestN
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return;
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}
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- // Skip the query host, type (2 bytes) and class (2 bytes).
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char host[PACKETSZ], answer[PACKETSZ];
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unsigned char *p = response + sizeof(HEADER);
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- int status = local_dn_expand(response, response + responseLength, p, host, sizeof(host));
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- if (status < 0) {
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+ int status;
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+
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+ if (ntohs(header->qdcount) == 1) {
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+ // Skip the query host, type (2 bytes) and class (2 bytes).
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+ status = local_dn_expand(response, response + responseLength, p, host, sizeof(host));
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+ if (status < 0) {
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+ reply->error = QDnsLookup::InvalidReplyError;
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+ reply->errorString = tr("Could not expand domain name");
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+ return;
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+ }
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+ if ((p - response) + status + 4 >= responseLength)
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+ header->qdcount = 0xffff; // invalid reply below
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+ else
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+ p += status + 4;
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+ }
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+ if (ntohs(header->qdcount) > 1) {
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reply->error = QDnsLookup::InvalidReplyError;
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- reply->errorString = tr("Could not expand domain name");
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+ reply->errorString = tr("Invalid reply received");
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return;
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}
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- p += status + 4;
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// Extract results.
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+ const int answerCount = ntohs(header->ancount);
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int answerIndex = 0;
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while ((p < response + responseLength) && (answerIndex < answerCount)) {
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status = local_dn_expand(response, response + responseLength, p, host, sizeof(host));
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@@ -283,6 +295,11 @@ void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestN
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const QString name = QUrl::fromAce(host);
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p += status;
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+
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+ if ((p - response) + 10 > responseLength) {
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+ // probably just a truncated reply, return what we have
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+ return;
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+ }
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const quint16 type = (p[0] << 8) | p[1];
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p += 2; // RR type
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p += 2; // RR class
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@@ -290,6 +307,8 @@ void QDnsLookupRunnable::query(const int requestType, const QByteArray &requestN
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p += 4;
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const quint16 size = (p[0] << 8) | p[1];
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p += 2;
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+ if ((p - response) + size > responseLength)
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+ return; // truncated
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if (type == QDnsLookup::A) {
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if (size != 4) {
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