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 EEBEE4F30CF for ; Wed, 16 Sep 2026 10:42:09 +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=1789555344; cv=none; b=dgf5fDLbR0aSrVPUswWqI4y0gZt9rc9spxlgPCI8MGH/035Am0UxYOA2jkS48zUMfDh8AyAP1n2cnIaF6+l67Cq2UCbJC6R/TFgPV0LbfdpROrVeMuXOKcLLYgCYpmt5r8VV7uLpTjtbHdOrEzge3TGcE0J0K0g25WBtLd5OfEA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789555344; c=relaxed/simple; bh=a+VV92k7JC23/kEvClz+nL3uo3MrSy+uLHGVfrHhW3w=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=t7PC4fPyiwTrCZO0lEwFccJb/VG5Wtoubw0nYr9dG9psNOXa/E0E4/Nucg7+x43qz/VI8waaUMIW1UJ48H7UPy6mAnUijUAJTVSZFCoqqoS0z+jF/Q273Hlqp5S2mB6ACCRybfE26te1OTJCTUT/++FUsDNQADpSIBGODFpuVjw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yZvIYFli; 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="yZvIYFli" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A2E491F000FF; Wed, 16 Sep 2026 10:42:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789555326; bh=kUjx0+lg4kSHkrTfcomkglXMG65ApYdUR3XDNcCXiTU=; h=From:To:Cc:Subject:Date:Reply-To; b=yZvIYFli5w5uoweDnZR6TEuRKv6qPuwSF6wp/QSLlAWmrrviVsRiXJr5k0CMwhNq1 ylnRkqKGM4+z/asR+oe5EcaaKT4VjNseaLpWIo7YlQH8yy7s0fYL7z+WHUVDZR7MAP N7orxWoMngdhzEtyijKi0Exf7YdC4BkAozq/qjco= From: Greg Kroah-Hartman To: linux-cve-announce@vger.kernel.org Cc: Greg Kroah-Hartman Subject: CVE-2026-89981: arm64: Don't read GMID_EL1 when MTE is disabled Date: Wed, 16 Sep 2026 11:31:51 +0100 Message-ID: <2026091655-CVE-2026-89981-da41@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=2779; i=gregkh@linuxfoundation.org; h=from:subject:message-id; bh=n4Gzb/z640csS9seWsILfbmOq+dMe/u1uEEpM3VzzXk=; b=owGbwMvMwCRo6H6F97bub03G02pJDFmr8hc/OPFV3LVOqyFDlIXFd8XMXt334Qm3Jmy7N9Mlk SNfb+bqjlgWBkEmBlkxRZYv23iO7q84pOhlaHsaZg4rE8gQBi5OAZiIah7Dgmkn8macu3YpYW94 yjoVrkf/f9VkNDPMFVkYOj9ZUD3Qa/K97ayMRxXrHIKkAA== 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: arm64: Don't read GMID_EL1 when MTE is disabled __cpuinfo_store_cpu() gates the GMID_EL1 read on the raw ID_AA64PFR1_EL1, so it reads the register even when the kernel has disabled MTE (CONFIG_ARM64_MTE=n or arm64.nomte). KVM sets HCR_EL2.TID5 in that case, and pKVM injects an UNDEF the host cannot handle: Internal error: Oops - Undefined instruction: 0000000002000000 [#1] SMP pc : __cpuinfo_store_cpu+0xf4/0x264 Kernel panic - not syncing: Attempted to kill the idle task! Only pKVM reaches it, and only after a CPU is offlined and brought back online: its CPU_ON relay sets the host HCR before the CPU enters EL1, while plain nVHE sets it at CPUHP_AP_KVM_ONLINE. Gate the read on the CPU's own ID_AA64PFR1_EL1 with the command-line override applied, and on CONFIG_ARM64_MTE, which no register reflects. The boot CPU stores its registers before init_cpu_features() strips an unsafe override, so clamp against the hardware value here too. The Linux kernel CVE team has assigned CVE-2026-89981 to this issue. Affected and fixed versions =========================== Issue introduced in 7.0 with commit f35abcbb8a084db4c24b66ccc8db0405c08e2f61 and fixed in 7.2.5 with commit d2d22ff377cd43f2e9660426ff22e3cd4c534637 Issue introduced in 7.0 with commit f35abcbb8a084db4c24b66ccc8db0405c08e2f61 and fixed in 7.3-rc2 with commit 5445d64199626974269fcdf347769ad44b0bb53b 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-2026-89981 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/arm64/include/asm/cpu.h arch/arm64/include/asm/cpufeature.h arch/arm64/kernel/cpufeature.c arch/arm64/kernel/cpuinfo.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/d2d22ff377cd43f2e9660426ff22e3cd4c534637 https://git.kernel.org/stable/c/5445d64199626974269fcdf347769ad44b0bb53b