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From d3602e5afa1e90c5e33625fc528db7f96195bada Mon Sep 17 00:00:00 2001
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From: Jon Maloy <jmaloy@redhat.com>
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Date: Mon, 7 Nov 2022 19:59:46 -0500
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Subject: [PATCH 42/42] ui/vnc-clipboard: fix integer underflow in
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vnc_client_cut_text_ext
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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RH-Author: Jon Maloy <jmaloy@redhat.com>
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RH-MergeRequest: 227: ui/vnc-clipboard: fix integer underflow in vnc_client_cut_text_ext
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RH-Bugzilla: 2129760
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RH-Acked-by: Mauro Matteo Cascella <None>
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RH-Acked-by: Marc-André Lureau <marcandre.lureau@redhat.com>
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RH-Acked-by: Thomas Huth <thuth@redhat.com>
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RH-Acked-by: Gerd Hoffmann <kraxel@redhat.com>
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RH-Commit: [1/1] ac19a6c0777e308061bcb6d1de5cc9beaa105a3a (jmaloy/qemu-kvm)
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BZ: https://bugzilla.redhat.com/show_bug.cgi?id=2129760
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CVE: CVE-2022-3165
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Upstream: Merged
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commit d307040b18bfcb1393b910f1bae753d5c12a4dc7
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Author: Mauro Matteo Cascella <mcascell@redhat.com>
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Date: Sun Sep 25 22:45:11 2022 +0200
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ui/vnc-clipboard: fix integer underflow in vnc_client_cut_text_ext
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Extended ClientCutText messages start with a 4-byte header. If len < 4,
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an integer underflow occurs in vnc_client_cut_text_ext. The result is
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used to decompress data in a while loop in inflate_buffer, leading to
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CPU consumption and denial of service. Prevent this by checking dlen in
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protocol_client_msg.
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Fixes: CVE-2022-3165
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Fixes: 0bf41cab93e5 ("ui/vnc: clipboard support")
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Reported-by: TangPeng <tangpeng@qianxin.com>
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Signed-off-by: Mauro Matteo Cascella <mcascell@redhat.com>
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Message-Id: <20220925204511.1103214-1-mcascell@redhat.com>
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Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
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(cherry picked from commit d307040b18bfcb1393b910f1bae753d5c12a4dc7)
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Signed-off-by: Jon Maloy <jmaloy@redhat.com>
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---
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ui/vnc.c | 11 ++++++++---
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1 file changed, 8 insertions(+), 3 deletions(-)
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diff --git a/ui/vnc.c b/ui/vnc.c
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index af02522e84..a14b6861be 100644
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--- a/ui/vnc.c
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+++ b/ui/vnc.c
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@@ -2442,8 +2442,8 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
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if (len == 1) {
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return 8;
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}
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+ uint32_t dlen = abs(read_s32(data, 4));
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if (len == 8) {
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- uint32_t dlen = abs(read_s32(data, 4));
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if (dlen > (1 << 20)) {
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error_report("vnc: client_cut_text msg payload has %u bytes"
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" which exceeds our limit of 1MB.", dlen);
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@@ -2456,8 +2456,13 @@ static int protocol_client_msg(VncState *vs, uint8_t *data, size_t len)
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}
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if (read_s32(data, 4) < 0) {
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- vnc_client_cut_text_ext(vs, abs(read_s32(data, 4)),
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- read_u32(data, 8), data + 12);
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+ if (dlen < 4) {
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+ error_report("vnc: malformed payload (header less than 4 bytes)"
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+ " in extended clipboard pseudo-encoding.");
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+ vnc_client_error(vs);
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+ break;
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+ }
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+ vnc_client_cut_text_ext(vs, dlen, read_u32(data, 8), data + 12);
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break;
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}
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vnc_client_cut_text(vs, read_u32(data, 4), data + 8);
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--
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2.37.3
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