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36 lines
1.0 KiB
36 lines
1.0 KiB
2 years ago
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From 11beef0b7f1ed290348e45618e5fa0d2bffcb72e Mon Sep 17 00:00:00 2001
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From: Peter Hutterer <peter.hutterer@who-t.net>
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Date: Tue, 5 Jul 2022 12:06:20 +1000
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Subject: [PATCH xserver] xkb: proof GetCountedString against request length
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attacks
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GetCountedString did a check for the whole string to be within the
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request buffer but not for the initial 2 bytes that contain the length
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field. A swapped client could send a malformed request to trigger a
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swaps() on those bytes, writing into random memory.
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Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>
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---
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xkb/xkb.c | 5 +++++
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1 file changed, 5 insertions(+)
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diff --git a/xkb/xkb.c b/xkb/xkb.c
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index f42f59ef3..1841cff26 100644
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--- a/xkb/xkb.c
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+++ b/xkb/xkb.c
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@@ -5137,6 +5137,11 @@ _GetCountedString(char **wire_inout, ClientPtr client, char **str)
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CARD16 len;
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wire = *wire_inout;
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+
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+ if (client->req_len <
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+ bytes_to_int32(wire + 2 - (char *) client->requestBuffer))
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+ return BadValue;
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+
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len = *(CARD16 *) wire;
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if (client->swapped) {
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swaps(&len);
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--
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2.38.1
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