From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 919A6288AD for ; Fri, 8 May 2026 14:25:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250341; cv=none; b=UQXfMufil2GXS2CjlWmy1tiiWyuaSB8Np5pRizCOvIHahKMZnLSHQuipDJdyyNAH1MGuYZrstiOdqJ82pXSW1iY6WWh/T3HRLafrMuzF0+pEbgUPItnBzN+lcY9tYndaRHZwokct6bNRcD3Y+tG8AZwWLS4iU2MyWIo633ygIzA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1778250341; c=relaxed/simple; bh=ST7gNHteji4/IjGZS3SKGbvDzySyQpA2uJZ9uXelIaM=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=Tb5YnyEcA3PdFQ+gxW1gt/uOx3mldcOh4ZZRAcd2D/KEYRsvXI3VB+/wQy3JbYbTZff4bD68MaGrCQ2dQ8G8Aaae+63EYBgnccHGbnn6vPZUlWTcFxRqPfuMyf1+Wj4E1RfPqFPkjbBua12++dKBbaEg6rE34XGW3haHw3VIRxs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mu6R4wVc; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mu6R4wVc" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E137FC2BCB0; Fri, 8 May 2026 14:25:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1778250341; bh=ST7gNHteji4/IjGZS3SKGbvDzySyQpA2uJZ9uXelIaM=; h=From:To:Cc:Subject:Date:Reply-To:From; b=mu6R4wVc6PROkjeT+58ra9Uvmbs3aD++d4GuNC1SnvCZ9awhlKX7IOhCrzoUj1U53 yhzfrzVDMcrlBmbngzfh7+EjjO8AOfq8FEn9BrvoDC4mjg19Ed8D7ifxG8Ox0gTkrk My2KYikVrOLtkxeTZRu7VcGWZ1LmWUkFR+33h4M8= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-43438: sched_ext: Remove redundant css_put() in scx_cgroup_init() Date: Fri, 8 May 2026 16:22:47 +0200 Message-ID: <2026050853-CVE-2026-43438-f2f2@gregkh> X-Mailer: git-send-email 2.54.0 Reply-To: , Precedence: bulk X-Mailing-List: linux-cve-announce@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=2775; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=COwjwj7OugOGKTQcjlorYcfjNC56psndV3zzHc0CKek=; b=owGbwMvMwCRo6H6F97bub03G02pJDJl/PzZGrM2fq9j9dFVkqkaSwKTsq8JPWtL1F57ntjpU7 pHwVUG4I5aFQZCJQVZMkeXLNp6j+ysOKXoZ2p6GmcPKBDKEgYtTACaybxHDgrNRJ4vUgmo0l3OZ tyYfkM2uPXjPkWGegeod++ez7mY8CXC7/2ZX5bnA+WLhAA== X-Developer-Key: i=gregkh@linuxfoundation.org; a=openpgp; fpr=F4B60CC5BF78C2214A313DCB3147D40DDB2DFB29 Content-Transfer-Encoding: 8bit From: Greg Kroah-Hartman Description =========== In the Linux kernel, the following vulnerability has been resolved: sched_ext: Remove redundant css_put() in scx_cgroup_init() The iterator css_for_each_descendant_pre() walks the cgroup hierarchy under cgroup_lock(). It does not increment the reference counts on yielded css structs. According to the cgroup documentation, css_put() should only be used to release a reference obtained via css_get() or css_tryget_online(). Since the iterator does not use either of these to acquire a reference, calling css_put() in the error path of scx_cgroup_init() causes a refcount underflow. Remove the unbalanced css_put() to prevent a potential Use-After-Free (UAF) vulnerability. The Linux kernel CVE team has assigned CVE-2026-43438 to this issue. Affected and fixed versions =========================== Issue introduced in 6.12 with commit 8195136669661fdfe54e9a8923c33b31c92fc1da and fixed in 6.12.78 with commit cc095cd305fddbe25a968e4a78436ff9476cf0f6 Issue introduced in 6.12 with commit 8195136669661fdfe54e9a8923c33b31c92fc1da and fixed in 6.18.19 with commit 6eaaa67d6998f6c30c462b140db8c062e07ec473 Issue introduced in 6.12 with commit 8195136669661fdfe54e9a8923c33b31c92fc1da and fixed in 6.19.9 with commit bf50f3285eda8a0173625fcdb5f183f96e1008cd Issue introduced in 6.12 with commit 8195136669661fdfe54e9a8923c33b31c92fc1da and fixed in 7.0 with commit 1336b579f6079fb8520be03624fcd9ba443c930b Please see https://www.kernel.org for a full list of currently supported kernel versions by the kernel community. Unaffected versions might change over time as fixes are backported to older supported kernel versions. The official CVE entry at https://cve.org/CVERecord/?id=CVE-2026-43438 will be updated if fixes are backported, please check that for the most up to date information about this issue. Affected files ============== The file(s) affected by this issue are: kernel/sched/ext.c Mitigation ========== The Linux kernel CVE team recommends that you update to the latest stable kernel version for this, and many other bugfixes. Individual changes are never tested alone, but rather are part of a larger kernel release. Cherry-picking individual commits is not recommended or supported by the Linux kernel community at all. If however, updating to the latest release is impossible, the individual changes to resolve this issue can be found at these commits: https://git.kernel.org/stable/c/cc095cd305fddbe25a968e4a78436ff9476cf0f6 https://git.kernel.org/stable/c/6eaaa67d6998f6c30c462b140db8c062e07ec473 https://git.kernel.org/stable/c/bf50f3285eda8a0173625fcdb5f183f96e1008cd https://git.kernel.org/stable/c/1336b579f6079fb8520be03624fcd9ba443c930b