From d3602e5afa1e90c5e33625fc528db7f96195bada Mon Sep 17 00:00:00 2001
From: Jon Maloy <jmaloy@redhat.com>
Date: Mon, 7 Nov 2022 19:59:46 -0500
Subject: [PATCH 42/42] ui/vnc-clipboard: fix integer underflow in
vnc_client_cut_text_ext
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RH-Author: Jon Maloy <jmaloy@redhat.com>
RH-MergeRequest: 227: ui/vnc-clipboard: fix integer underflow in vnc_client_cut_text_ext
RH-Bugzilla: 2129760
RH-Acked-by: Mauro Matteo Cascella <None>
RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>
RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
RH-Commit: [1/1] ac19a6c0777e308061bcb6d1de5cc9beaa105a3a (jmaloy/qemu-kvm)
BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2129760
CVE: CVE-2022-3165
Upstream: Merged
commit d307040b18bfcb1393b910f1bae753d5c12a4dc7
Author: Mauro Matteo Cascella <mcascell@redhat.com>
Date: Sun Sep 25 22:45:11 2022 +0200
ui/vnc-clipboard: fix integer underflow in vnc_client_cut_text_ext
Extended ClientCutText messages start with a 4-byte header. If len < 4,
an integer underflow occurs in vnc_client_cut_text_ext. The result is
used to decompress data in a while loop in inflate_buffer, leading to
CPU consumption and denial of service. Prevent this by checking dlen in
protocol_client_msg.
Fixes: CVE-2022-3165
Fixes: 0bf41cab93e5 ("ui/vnc: clipboard support")
Reported-by: TangPeng <tangpeng@qianxin.com>
Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
Message-Id: <20220925204511.1103214-1-mcascell@redhat.com>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
(cherry picked from commit d307040b18bfcb1393b910f1bae753d5c12a4dc7)
Signed-off-by: Jon Maloy <jmaloy@redhat.com>
---
ui/vnc.c | 11 ++++++++---
1 file changed, 8 insertions(+), 3 deletions(-)
diff --git a/ui/vnc.c b/ui/vnc.c
index af02522e84..a14b6861be 100644
--- a/ui/vnc.c
+++ b/ui/vnc.c
@@ -2442,8 +2442,8 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
if (len == 1) {
return 8;
}
+ uint32_t dlen = abs(read_s32(data, 4));
if (len == 8) {
- uint32_t dlen = abs(read_s32(data, 4));
if (dlen > (1 << 20)) {
error_report("vnc: client_cut_text msg payload has %u bytes"
" which exceeds our limit of 1MB.", dlen);
@@ -2456,8 +2456,13 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
}
if (read_s32(data, 4) < 0) {
- vnc_client_cut_text_ext(vs, abs(read_s32(data, 4)),
- read_u32(data, 8), data + 12);
+ if (dlen < 4) {
+ error_report("vnc: malformed payload (header less than 4 bytes)"
+ " in extended clipboard pseudo-encoding.");
+ vnc_client_error(vs);
+ break;
+ }
+ vnc_client_cut_text_ext(vs, dlen, read_u32(data, 8), data + 12);
break;
}
vnc_client_cut_text(vs, read_u32(data, 4), data + 8);
--
2.37.3