From 9f60a166460c7c864e969ec4290693c62d6f4484 Mon Sep 17 00:00:00 2001 From: Simone Weiß Date: Sat, 2 Mar 2024 16:40:52 +0000 Subject: qemu: backport patch for ui/clipboard issue MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Backported from upstream to fix CVE-2023-6683 (From OE-Core rev: d33a0ef657663faa05448454fad8a004879fe624) Signed-off-by: Simone Weiß Signed-off-by: Richard Purdie --- meta/recipes-devtools/qemu/qemu.inc | 1 + .../recipes-devtools/qemu/qemu/CVE-2023-6683.patch | 91 ++++++++++++++++++++++ 2 files changed, 92 insertions(+) create mode 100644 meta/recipes-devtools/qemu/qemu/CVE-2023-6683.patch diff --git a/meta/recipes-devtools/qemu/qemu.inc b/meta/recipes-devtools/qemu/qemu.inc index b42cc120f1..4501f84c2b 100644 --- a/meta/recipes-devtools/qemu/qemu.inc +++ b/meta/recipes-devtools/qemu/qemu.inc @@ -39,6 +39,7 @@ SRC_URI = "https://download.qemu.org/${BPN}-${PV}.tar.xz \ file://0003-linux-user-Add-strace-for-shmat.patch \ file://0004-linux-user-Rewrite-target_shmat.patch \ file://0005-tests-tcg-Check-that-shmat-does-not-break-proc-self-.patch \ + file://CVE-2023-6683.patch \ file://qemu-guest-agent.init \ file://qemu-guest-agent.udev \ " diff --git a/meta/recipes-devtools/qemu/qemu/CVE-2023-6683.patch b/meta/recipes-devtools/qemu/qemu/CVE-2023-6683.patch new file mode 100644 index 0000000000..732cb6af18 --- /dev/null +++ b/meta/recipes-devtools/qemu/qemu/CVE-2023-6683.patch @@ -0,0 +1,91 @@ +From 405484b29f6548c7b86549b0f961b906337aa68a Mon Sep 17 00:00:00 2001 +From: Fiona Ebner +Date: Wed, 24 Jan 2024 11:57:48 +0100 +Subject: [PATCH] ui/clipboard: mark type as not available when there is no + data +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +With VNC, a client can send a non-extended VNC_MSG_CLIENT_CUT_TEXT +message with len=0. In qemu_clipboard_set_data(), the clipboard info +will be updated setting data to NULL (because g_memdup(data, size) +returns NULL when size is 0). If the client does not set the +VNC_ENCODING_CLIPBOARD_EXT feature when setting up the encodings, then +the 'request' callback for the clipboard peer is not initialized. +Later, because data is NULL, qemu_clipboard_request() can be reached +via vdagent_chr_write() and vdagent_clipboard_recv_request() and +there, the clipboard owner's 'request' callback will be attempted to +be called, but that is a NULL pointer. + +In particular, this can happen when using the KRDC (22.12.3) VNC +client. + +Another scenario leading to the same issue is with two clients (say +noVNC and KRDC): + +The noVNC client sets the extension VNC_FEATURE_CLIPBOARD_EXT and +initializes its cbpeer. + +The KRDC client does not, but triggers a vnc_client_cut_text() (note +it's not the _ext variant)). There, a new clipboard info with it as +the 'owner' is created and via qemu_clipboard_set_data() is called, +which in turn calls qemu_clipboard_update() with that info. + +In qemu_clipboard_update(), the notifier for the noVNC client will be +called, i.e. vnc_clipboard_notify() and also set vs->cbinfo for the +noVNC client. The 'owner' in that clipboard info is the clipboard peer +for the KRDC client, which did not initialize the 'request' function. +That sounds correct to me, it is the owner of that clipboard info. + +Then when noVNC sends a VNC_MSG_CLIENT_CUT_TEXT message (it did set +the VNC_FEATURE_CLIPBOARD_EXT feature correctly, so a check for it +passes), that clipboard info is passed to qemu_clipboard_request() and +the original segfault still happens. + +Fix the issue by handling updates with size 0 differently. In +particular, mark in the clipboard info that the type is not available. + +While at it, switch to g_memdup2(), because g_memdup() is deprecated. + +Cc: qemu-stable@nongnu.org +Fixes: CVE-2023-6683 +Reported-by: Markus Frank +Suggested-by: Marc-André Lureau +Signed-off-by: Fiona Ebner +Reviewed-by: Marc-André Lureau +Tested-by: Markus Frank +Message-ID: <20240124105749.204610-1-f.ebner@proxmox.com> + +CVE: CVE-2023-6683 + +Upstream-Status: Backport [https://github.com/qemu/qemu/commit/405484b29f6548c7b86549b0f961b906337aa68a] +Signed-off-by: Simone Weiß + +--- + ui/clipboard.c | 12 +++++++++--- + 1 file changed, 9 insertions(+), 3 deletions(-) + +diff --git a/ui/clipboard.c b/ui/clipboard.c +index 3d14bffaf80f..b3f6fa3c9e1f 100644 +--- a/ui/clipboard.c ++++ b/ui/clipboard.c +@@ -163,9 +163,15 @@ void qemu_clipboard_set_data(QemuClipboardPeer *peer, + } + + g_free(info->types[type].data); +- info->types[type].data = g_memdup(data, size); +- info->types[type].size = size; +- info->types[type].available = true; ++ if (size) { ++ info->types[type].data = g_memdup2(data, size); ++ info->types[type].size = size; ++ info->types[type].available = true; ++ } else { ++ info->types[type].data = NULL; ++ info->types[type].size = 0; ++ info->types[type].available = false; ++ } + + if (update) { + qemu_clipboard_update(info); -- cgit v1.2.3-54-g00ecf