65 lines
2.2 KiB
Diff
65 lines
2.2 KiB
Diff
From d943eaa6b8584e7ceebd73ee59bd84e99b09be5d Mon Sep 17 00:00:00 2001
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From: Olivier Fourdan <ofourdan@redhat.com>
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Date: Mon, 28 Apr 2025 11:47:15 +0200
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Subject: [PATCH xserver 5/7] record: Check for overflow in
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RecordSanityCheckRegisterClients()
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The RecordSanityCheckRegisterClients() checks for the request length,
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but does not check for integer overflow.
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A client might send a very large value for either the number of clients
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or the number of protocol ranges that will cause an integer overflow in
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the request length computation, defeating the check for request length.
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To avoid the issue, explicitly check the number of clients against the
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limit of clients (which is much lower than an maximum integer value) and
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the number of protocol ranges (multiplied by the record length) do not
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exceed the maximum integer value.
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This way, we ensure that the final computation for the request length
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will not overflow the maximum integer limit.
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CVE-2025-49179
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This issue was discovered by Nils Emmerich <nemmerich@ernw.de> and
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reported by Julian Suleder via ERNW Vulnerability Disclosure.
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Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>
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Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
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(cherry picked from commit 2bde9ca49a8fd9a1e6697d5e7ef837870d66f5d4)
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Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/2025>
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---
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record/record.c | 8 ++++++++
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1 file changed, 8 insertions(+)
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diff --git a/record/record.c b/record/record.c
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index a8aec23bd..afaceb55c 100644
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--- a/record/record.c
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+++ b/record/record.c
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@@ -45,6 +45,7 @@ and Jim Haggerty of Metheus.
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#include "inputstr.h"
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#include "eventconvert.h"
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#include "scrnintstr.h"
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+#include "opaque.h"
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#include <stdio.h>
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#include <assert.h>
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@@ -1298,6 +1299,13 @@ RecordSanityCheckRegisterClients(RecordContextPtr pContext, ClientPtr client,
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int i;
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XID recordingClient;
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+ /* LimitClients is 2048 at max, way less that MAXINT */
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+ if (stuff->nClients > LimitClients)
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+ return BadValue;
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+
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+ if (stuff->nRanges > (MAXINT - 4 * stuff->nClients) / SIZEOF(xRecordRange))
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+ return BadValue;
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+
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if (((client->req_len << 2) - SIZEOF(xRecordRegisterClientsReq)) !=
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4 * stuff->nClients + SIZEOF(xRecordRange) * stuff->nRanges)
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return BadLength;
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--
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2.49.0
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