| CVE: CVE-2022-3165 |
| Upstream-Status: Backport |
| Signed-off-by: Ross Burton <ross.burton@arm.com> |
| |
| From d307040b18bfcb1393b910f1bae753d5c12a4dc7 Mon Sep 17 00:00:00 2001 |
| From: Mauro Matteo Cascella <mcascell@redhat.com> |
| Date: Sun, 25 Sep 2022 22:45:11 +0200 |
| Subject: [PATCH] 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> |
| --- |
| ui/vnc.c | 11 ++++++++--- |
| 1 file changed, 8 insertions(+), 3 deletions(-) |
| |
| diff --git a/ui/vnc.c b/ui/vnc.c |
| index 6a05d06147..acb3629cd8 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); |
| -- |
| GitLab |
| |