From adc46abef0b2d3621a83b9affa784b928a7ef2b3 Mon Sep 17 00:00:00 2001 From: Dietmar Maurer Date: Fri, 30 Oct 2015 09:50:36 +0100 Subject: [PATCH] fix CVE-2015-1779, bump version to 2.2-13 --- Makefile | 2 +- debian/changelog | 6 + ...ncrementally-decode-websocket-frames.patch | 241 ++++++++++++++++++ ...HTTP-headers-from-websockets-clients.patch | 58 +++++ debian/patches/series | 2 + 5 files changed, 308 insertions(+), 1 deletion(-) create mode 100644 debian/patches/CVE-2015-1779-incrementally-decode-websocket-frames.patch create mode 100644 debian/patches/CVE-2015-1779-limit-size-of-HTTP-headers-from-websockets-clients.patch diff --git a/Makefile b/Makefile index d62446d..05d46ac 100644 --- a/Makefile +++ b/Makefile @@ -2,7 +2,7 @@ RELEASE=3.4 # also update debian/changelog KVMVER=2.2 -KVMPKGREL=12 +KVMPKGREL=13 KVMPACKAGE=pve-qemu-kvm KVMDIR=qemu-kvm diff --git a/debian/changelog b/debian/changelog index e6cf541..92dff6d 100644 --- a/debian/changelog +++ b/debian/changelog @@ -1,3 +1,9 @@ +pve-qemu-kvm (2.2-13) unstable; urgency=low + + * fix CVE-2015-1779 + + -- Proxmox Support Team Fri, 30 Oct 2015 09:50:10 +0100 + pve-qemu-kvm (2.2-12) unstable; urgency=low * added ne2000 patch diff --git a/debian/patches/CVE-2015-1779-incrementally-decode-websocket-frames.patch b/debian/patches/CVE-2015-1779-incrementally-decode-websocket-frames.patch new file mode 100644 index 0000000..ffa4a9a --- /dev/null +++ b/debian/patches/CVE-2015-1779-incrementally-decode-websocket-frames.patch @@ -0,0 +1,241 @@ +From a2bebfd6e09d285aa793cae3fb0fc3a39a9fee6e Mon Sep 17 00:00:00 2001 +From: "Daniel P. Berrange" +Date: Mon, 23 Mar 2015 22:58:21 +0000 +Subject: [PATCH 1/2] CVE-2015-1779: incrementally decode websocket frames + +The logic for decoding websocket frames wants to fully +decode the frame header and payload, before allowing the +VNC server to see any of the payload data. There is no +size limit on websocket payloads, so this allows a +malicious network client to consume 2^64 bytes in memory +in QEMU. It can trigger this denial of service before +the VNC server even performs any authentication. + +The fix is to decode the header, and then incrementally +decode the payload data as it is needed. With this fix +the websocket decoder will allow at most 4k of data to +be buffered before decoding and processing payload. + +Signed-off-by: Daniel P. Berrange + +[ kraxel: fix frequent spurious disconnects, suggested by Peter Maydell ] + + @@ -361,7 +361,7 @@ int vncws_decode_frame_payload(Buffer *input, + - *payload_size = input->offset; + + *payload_size = *payload_remain; + +[ kraxel: fix 32bit build ] + + @@ -306,7 +306,7 @@ struct VncState + - uint64_t ws_payload_remain; + + size_t ws_payload_remain; + +Signed-off-by: Gerd Hoffmann +--- + ui/vnc-ws.c | 105 ++++++++++++++++++++++++++++++++++++++++-------------------- + ui/vnc-ws.h | 9 ++++-- + ui/vnc.h | 2 ++ + 3 files changed, 80 insertions(+), 36 deletions(-) + +diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c +index 85dbb7e..0b7de4e 100644 +--- a/ui/vnc-ws.c ++++ b/ui/vnc-ws.c +@@ -107,7 +107,7 @@ long vnc_client_read_ws(VncState *vs) + { + int ret, err; + uint8_t *payload; +- size_t payload_size, frame_size; ++ size_t payload_size, header_size; + VNC_DEBUG("Read websocket %p size %zd offset %zd\n", vs->ws_input.buffer, + vs->ws_input.capacity, vs->ws_input.offset); + buffer_reserve(&vs->ws_input, 4096); +@@ -117,18 +117,39 @@ long vnc_client_read_ws(VncState *vs) + } + vs->ws_input.offset += ret; + +- /* make sure that nothing is left in the ws_input buffer */ ++ ret = 0; ++ /* consume as much of ws_input buffer as possible */ + do { +- err = vncws_decode_frame(&vs->ws_input, &payload, +- &payload_size, &frame_size); +- if (err <= 0) { +- return err; ++ if (vs->ws_payload_remain == 0) { ++ err = vncws_decode_frame_header(&vs->ws_input, ++ &header_size, ++ &vs->ws_payload_remain, ++ &vs->ws_payload_mask); ++ if (err <= 0) { ++ return err; ++ } ++ ++ buffer_advance(&vs->ws_input, header_size); + } ++ if (vs->ws_payload_remain != 0) { ++ err = vncws_decode_frame_payload(&vs->ws_input, ++ &vs->ws_payload_remain, ++ &vs->ws_payload_mask, ++ &payload, ++ &payload_size); ++ if (err < 0) { ++ return err; ++ } ++ if (err == 0) { ++ return ret; ++ } ++ ret += err; + +- buffer_reserve(&vs->input, payload_size); +- buffer_append(&vs->input, payload, payload_size); ++ buffer_reserve(&vs->input, payload_size); ++ buffer_append(&vs->input, payload, payload_size); + +- buffer_advance(&vs->ws_input, frame_size); ++ buffer_advance(&vs->ws_input, payload_size); ++ } + } while (vs->ws_input.offset > 0); + + return ret; +@@ -265,15 +286,14 @@ void vncws_encode_frame(Buffer *output, const void *payload, + buffer_append(output, payload, payload_size); + } + +-int vncws_decode_frame(Buffer *input, uint8_t **payload, +- size_t *payload_size, size_t *frame_size) ++int vncws_decode_frame_header(Buffer *input, ++ size_t *header_size, ++ size_t *payload_remain, ++ WsMask *payload_mask) + { + unsigned char opcode = 0, fin = 0, has_mask = 0; +- size_t header_size = 0; +- uint32_t *payload32; ++ size_t payload_len; + WsHeader *header = (WsHeader *)input->buffer; +- WsMask mask; +- int i; + + if (input->offset < WS_HEAD_MIN_LEN + 4) { + /* header not complete */ +@@ -283,7 +303,7 @@ int vncws_decode_frame(Buffer *input, uint8_t **payload, + fin = (header->b0 & 0x80) >> 7; + opcode = header->b0 & 0x0f; + has_mask = (header->b1 & 0x80) >> 7; +- *payload_size = header->b1 & 0x7f; ++ payload_len = header->b1 & 0x7f; + + if (opcode == WS_OPCODE_CLOSE) { + /* disconnect */ +@@ -300,40 +320,57 @@ int vncws_decode_frame(Buffer *input, uint8_t **payload, + return -2; + } + +- if (*payload_size < 126) { +- header_size = 6; +- mask = header->u.m; +- } else if (*payload_size == 126 && input->offset >= 8) { +- *payload_size = be16_to_cpu(header->u.s16.l16); +- header_size = 8; +- mask = header->u.s16.m16; +- } else if (*payload_size == 127 && input->offset >= 14) { +- *payload_size = be64_to_cpu(header->u.s64.l64); +- header_size = 14; +- mask = header->u.s64.m64; ++ if (payload_len < 126) { ++ *payload_remain = payload_len; ++ *header_size = 6; ++ *payload_mask = header->u.m; ++ } else if (payload_len == 126 && input->offset >= 8) { ++ *payload_remain = be16_to_cpu(header->u.s16.l16); ++ *header_size = 8; ++ *payload_mask = header->u.s16.m16; ++ } else if (payload_len == 127 && input->offset >= 14) { ++ *payload_remain = be64_to_cpu(header->u.s64.l64); ++ *header_size = 14; ++ *payload_mask = header->u.s64.m64; + } else { + /* header not complete */ + return 0; + } + +- *frame_size = header_size + *payload_size; ++ return 1; ++} ++ ++int vncws_decode_frame_payload(Buffer *input, ++ size_t *payload_remain, WsMask *payload_mask, ++ uint8_t **payload, size_t *payload_size) ++{ ++ size_t i; ++ uint32_t *payload32; + +- if (input->offset < *frame_size) { +- /* frame not complete */ ++ *payload = input->buffer; ++ /* If we aren't at the end of the payload, then drop ++ * off the last bytes, so we're always multiple of 4 ++ * for purpose of unmasking, except at end of payload ++ */ ++ if (input->offset < *payload_remain) { ++ *payload_size = input->offset - (input->offset % 4); ++ } else { ++ *payload_size = *payload_remain; ++ } ++ if (*payload_size == 0) { + return 0; + } +- +- *payload = input->buffer + header_size; ++ *payload_remain -= *payload_size; + + /* unmask frame */ + /* process 1 frame (32 bit op) */ + payload32 = (uint32_t *)(*payload); + for (i = 0; i < *payload_size / 4; i++) { +- payload32[i] ^= mask.u; ++ payload32[i] ^= payload_mask->u; + } + /* process the remaining bytes (if any) */ + for (i *= 4; i < *payload_size; i++) { +- (*payload)[i] ^= mask.c[i % 4]; ++ (*payload)[i] ^= payload_mask->c[i % 4]; + } + + return 1; +diff --git a/ui/vnc-ws.h b/ui/vnc-ws.h +index ef229b7..14d4230 100644 +--- a/ui/vnc-ws.h ++++ b/ui/vnc-ws.h +@@ -83,7 +83,12 @@ long vnc_client_read_ws(VncState *vs); + void vncws_process_handshake(VncState *vs, uint8_t *line, size_t size); + void vncws_encode_frame(Buffer *output, const void *payload, + const size_t payload_size); +-int vncws_decode_frame(Buffer *input, uint8_t **payload, +- size_t *payload_size, size_t *frame_size); ++int vncws_decode_frame_header(Buffer *input, ++ size_t *header_size, ++ size_t *payload_remain, ++ WsMask *payload_mask); ++int vncws_decode_frame_payload(Buffer *input, ++ size_t *payload_remain, WsMask *payload_mask, ++ uint8_t **payload, size_t *payload_size); + + #endif /* __QEMU_UI_VNC_WS_H */ +diff --git a/ui/vnc.h b/ui/vnc.h +index e19ac39..3f7c6a9 100644 +--- a/ui/vnc.h ++++ b/ui/vnc.h +@@ -306,6 +306,8 @@ struct VncState + #ifdef CONFIG_VNC_WS + Buffer ws_input; + Buffer ws_output; ++ size_t ws_payload_remain; ++ WsMask ws_payload_mask; + #endif + /* current output mode information */ + VncWritePixels *write_pixels; +-- +2.1.4 + diff --git a/debian/patches/CVE-2015-1779-limit-size-of-HTTP-headers-from-websockets-clients.patch b/debian/patches/CVE-2015-1779-limit-size-of-HTTP-headers-from-websockets-clients.patch new file mode 100644 index 0000000..7f4aec7 --- /dev/null +++ b/debian/patches/CVE-2015-1779-limit-size-of-HTTP-headers-from-websockets-clients.patch @@ -0,0 +1,58 @@ +From 2cdb5e142fb93e875fa53c52864ef5eb8d5d8b41 Mon Sep 17 00:00:00 2001 +From: "Daniel P. Berrange" +Date: Mon, 23 Mar 2015 22:58:22 +0000 +Subject: [PATCH 2/2] CVE-2015-1779: limit size of HTTP headers from websockets + clients + +The VNC server websockets decoder will read and buffer data from +websockets clients until it sees the end of the HTTP headers, +as indicated by \r\n\r\n. In theory this allows a malicious to +trick QEMU into consuming an arbitrary amount of RAM. In practice, +because QEMU runs g_strstr_len() across the buffered header data, +it will spend increasingly long burning CPU time searching for +the substring match and less & less time reading data. So while +this does cause arbitrary memory growth, the bigger problem is +that QEMU will be burning 100% of available CPU time. + +A novnc websockets client typically sends headers of around +512 bytes in length. As such it is reasonable to place a 4096 +byte limit on the amount of data buffered while searching for +the end of HTTP headers. + +Signed-off-by: Daniel P. Berrange +Signed-off-by: Gerd Hoffmann +--- + ui/vnc-ws.c | 10 ++++++++-- + 1 file changed, 8 insertions(+), 2 deletions(-) + +diff --git a/ui/vnc-ws.c b/ui/vnc-ws.c +index 0b7de4e..62eb97f 100644 +--- a/ui/vnc-ws.c ++++ b/ui/vnc-ws.c +@@ -81,8 +81,11 @@ void vncws_handshake_read(void *opaque) + VncState *vs = opaque; + uint8_t *handshake_end; + long ret; +- buffer_reserve(&vs->ws_input, 4096); +- ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), 4096); ++ /* Typical HTTP headers from novnc are 512 bytes, so limiting ++ * total header size to 4096 is easily enough. */ ++ size_t want = 4096 - vs->ws_input.offset; ++ buffer_reserve(&vs->ws_input, want); ++ ret = vnc_client_read_buf(vs, buffer_end(&vs->ws_input), want); + + if (!ret) { + if (vs->csock == -1) { +@@ -99,6 +102,9 @@ void vncws_handshake_read(void *opaque) + vncws_process_handshake(vs, vs->ws_input.buffer, vs->ws_input.offset); + buffer_advance(&vs->ws_input, handshake_end - vs->ws_input.buffer + + strlen(WS_HANDSHAKE_END)); ++ } else if (vs->ws_input.offset >= 4096) { ++ VNC_DEBUG("End of headers not found in first 4096 bytes\n"); ++ vnc_client_error(vs); + } + } + +-- +2.1.4 + diff --git a/debian/patches/series b/debian/patches/series index e3b6c8b..c266de3 100644 --- a/debian/patches/series +++ b/debian/patches/series @@ -39,3 +39,5 @@ add-qmp-get-link-status.patch virtio-scsi_fix_assert.patch 0001-fdc-force-the-fifo-access-to-be-in-bounds-of-the-all.patch net-add-checks-to-validate-ring-buffer-pointers.patch +CVE-2015-1779-incrementally-decode-websocket-frames.patch +CVE-2015-1779-limit-size-of-HTTP-headers-from-websockets-clients.patch -- 2.39.2