From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 252883A6B6C for ; Sun, 19 Jul 2026 15:42:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784475750; cv=none; b=cOtW3U/zf0sXfnhTBNIA3Y67Np0fY4lw73eET9BEp/vVwF5YZvJ04MI3TAjAnrTpdDHlPdS4XDfc5bLlpUaXdFw6YM2cySYHi3CDNBu8FjEC3Qt1DI4C+5sb8fP3HAhLC7k7NK2fqA+9Tw84ol+CVVyFxH0u3s56klfoWNi3Rxg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784475750; c=relaxed/simple; bh=l8ZCYNg5HhRXkAwdPqV9bAPPVH+X0csa3Evx39x+Er8=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=EnGh5HjkDPzKoKL4xNL4QcN92i//HN5LcCqYM0vUDGtSICFZhA030RmmwclS30quxh9cOZ6/7EjfZCygL4tdUIrHCMjM9qkk6CeKGONa0UhRs9LW/kRBG4pvazvH1B0gRmXCPw26ISpfLB999h2b2u1fD1/nTC2jbCZVmRcexlo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=oO4UunKK; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="oO4UunKK" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 448BC1F000E9; Sun, 19 Jul 2026 15:42:28 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784475748; bh=gbVDEWKyVAj34fWzvSm7LipMs72kymMpsE7Oo33JPVc=; h=From:To:Cc:Subject:Date:Reply-To; b=oO4UunKKju+vivVeMm0P7NFd2SDgDR1jVAE60Sb/6be6rafpKywKyLn+rg5SEJwFz 43JvqaLcsspW0+im4hz5j3gfNatjBb7TGZktTW9r7y5/VXe5WwYxAjFnFKR1a+rRBF 3Flj8GMQM9vYMwUge76MIkltnToM2WrRqMsAWlok= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-64070: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Date: Sun, 19 Jul 2026 17:38:52 +0200 Message-ID: <2026071913-CVE-2026-64070-6db2@gregkh> X-Mailer: git-send-email 2.55.0 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=3062; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=gr2NSfdjfvOhCT6peQoTpoFyLIry8Mkh291I55qtp2Q=; b=owGbwMvMwCRo6H6F97bub03G02pJDFkx71NL818vnPVywmfelyq2TYIf5tvMFhCWtLsV8H1B6 rJPRj9VOmJZGASZGGTFFFm+bOM5ur/ikKKXoe1pmDmsTCBDGLg4BWAiew8xzC94c0Kx6LTs8rm5 uzgOvzbce/NN/AWG+T47m39bvGL63Ma2tjXizp2Vh94d3gYA 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: powerpc/hv-gpci: fix preempt count leak in sysfs show paths Four sysfs show() callbacks in hv-gpci take get_cpu_var(hv_gpci_reqb) (which calls preempt_disable()) but only call the matching put_cpu_var() on the error path under the 'out:' label. Every successful read leaks one preempt_disable(): processor_bus_topology_show() processor_config_show() affinity_domain_via_virtual_processor_show() affinity_domain_via_domain_show() (affinity_domain_via_partition_show() was already correct.) On a CONFIG_PREEMPT=y kernel, repeated reads raise preempt_count and eventually return to userspace with preemption still disabled. The next user-mode page fault then hits faulthandler_disabled() == 1, gets forced to SIGSEGV, and the resulting coredump trips 'BUG: scheduling while atomic' in call_usermodehelper_exec -> wait_for_completion_state -> schedule: BUG: scheduling while atomic: //0x00000004 ... __schedule_bug+0x6c/0x90 __schedule+0x58c/0x13a0 schedule+0x48/0x1a0 schedule_timeout+0x104/0x170 wait_for_completion_state+0x16c/0x330 call_usermodehelper_exec+0x254/0x2d0 vfs_coredump+0x1050/0x2590 get_signal+0xb9c/0xc80 do_notify_resume+0xf8/0x470 Add an out_success label that calls put_cpu_var() before returning the byte count, mirroring affinity_domain_via_partition_show(). The Linux kernel CVE team has assigned CVE-2026-64070 to this issue. Affected and fixed versions =========================== Issue introduced in 6.6 with commit 71f1c39647d8c9d4d54a861ec81f1ff17544bcb6 and fixed in 7.0.11 with commit 903409000a07ac8e31ffedeb8516f4f8d67150c8 Issue introduced in 6.6 with commit 71f1c39647d8c9d4d54a861ec81f1ff17544bcb6 and fixed in 7.1 with commit dbc30a57bd8e026995e9fa8e8c31cffd18542c01 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-2026-64070 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: arch/powerpc/perf/hv-gpci.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/903409000a07ac8e31ffedeb8516f4f8d67150c8 https://git.kernel.org/stable/c/dbc30a57bd8e026995e9fa8e8c31cffd18542c01