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 E1B0932C85; Wed, 21 May 2025 05:50:06 +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=1747806607; cv=none; b=nkNU4OT9c2aOFA6MJTo3XvbiaUJ6bSG6RgIDtd0NgchhZo7nihRDOUYmr5883G5wYWK2aYyEEoZrxeqgkmpU5qcJV03CB6lzswwy9Jt8PmpPYco1QZi0hkr82JvIwJ1PiUhJkkn1r8sXQgtUNkI1jwVnOKxMVON0A0LH6txeXm0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1747806607; c=relaxed/simple; bh=EFmnDPRWmHTBUBaRYDRiICbXdWNSB1+AEE1/C/WzVtI=; h=Date:To:From:Subject:Message-Id; b=Exl6FeDY/AYtpzMxBSY77XmGo5nV2nBDmWmUeWHwpZXHsxV5PD7H0kCimfnKUttW2Ph9LSHe3XGNb3aYRBJggNrKU8diPy772JtHycFmXP60eisK09erR0/ybSWQC5oAu3a1n6S1hFqJmNk7Sd8othrcsK/kHGl34Tx4BE9s5+M= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b=ay1NaLye; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux-foundation.org header.i=@linux-foundation.org header.b="ay1NaLye" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 4497AC4CEE4; Wed, 21 May 2025 05:50:06 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1747806606; bh=EFmnDPRWmHTBUBaRYDRiICbXdWNSB1+AEE1/C/WzVtI=; h=Date:To:From:Subject:From; b=ay1NaLye4I2MK77eP2xnV3DRxtGwSpdji8SenB4gmo2fDEzxDdUFVEItoPp/loklE oKA5gtGCEwMcDvo5FQ+73n/KRRFVnHj7bXRM1PIkzSQGV31W7h78SEeecVCMJgKo/r WFb7FR6iS8Ue0aadQgpXwjEQdFVObgaaEGhbslDI= Date: Tue, 20 May 2025 22:50:05 -0700 To: mm-commits@vger.kernel.org,will@kernel.org,thiago.bauermann@linaro.org,tglx@linutronix.de,stable@vger.kernel.org,mingo@redhat.com,jackmanb@google.com,hpa@zytor.com,catalin.marinas@arm.com,broonie@kernel.org,bp@alien8.de,revest@chromium.org,akpm@linux-foundation.org From: Andrew Morton Subject: [merged mm-hotfixes-stable] mm-fix-vm_uffd_minor-==-vm_shadow_stack-on-userfaultfd=y-arm64_gcs=y.patch removed from -mm tree Message-Id: <20250521055006.4497AC4CEE4@smtp.kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: The quilt patch titled Subject: mm: fix VM_UFFD_MINOR == VM_SHADOW_STACK on USERFAULTFD=y && ARM64_GCS=y has been removed from the -mm tree. Its filename was mm-fix-vm_uffd_minor-==-vm_shadow_stack-on-userfaultfd=y-arm64_gcs=y.patch This patch was dropped because it was merged into the mm-hotfixes-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Florent Revest Subject: mm: fix VM_UFFD_MINOR == VM_SHADOW_STACK on USERFAULTFD=y && ARM64_GCS=y Date: Wed, 7 May 2025 15:09:57 +0200 On configs with CONFIG_ARM64_GCS=y, VM_SHADOW_STACK is bit 38. On configs with CONFIG_HAVE_ARCH_USERFAULTFD_MINOR=y (selected by CONFIG_ARM64 when CONFIG_USERFAULTFD=y), VM_UFFD_MINOR is _also_ bit 38. This bit being shared by two different VMA flags could lead to all sorts of unintended behaviors. Presumably, a process could maybe call into userfaultfd in a way that disables the shadow stack vma flag. I can't think of any attack where this would help (presumably, if an attacker tries to disable shadow stacks, they are trying to hijack control flow so can't arbitrarily call into userfaultfd yet anyway) but this still feels somewhat scary. Link: https://lkml.kernel.org/r/20250507131000.1204175-2-revest@chromium.org Fixes: ae80e1629aea ("mm: Define VM_SHADOW_STACK for arm64 when we support GCS") Signed-off-by: Florent Revest Reviewed-by: Mark Brown Cc: Borislav Betkov Cc: Brendan Jackman Cc: Catalin Marinas Cc: Florent Revest Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: Thiago Jung Bauermann Cc: Thomas Gleinxer Cc: Will Deacon Cc: Signed-off-by: Andrew Morton --- include/linux/mm.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/include/linux/mm.h~mm-fix-vm_uffd_minor-==-vm_shadow_stack-on-userfaultfd=y-arm64_gcs=y +++ a/include/linux/mm.h @@ -385,7 +385,7 @@ extern unsigned int kobjsize(const void #endif #ifdef CONFIG_HAVE_ARCH_USERFAULTFD_MINOR -# define VM_UFFD_MINOR_BIT 38 +# define VM_UFFD_MINOR_BIT 41 # define VM_UFFD_MINOR BIT(VM_UFFD_MINOR_BIT) /* UFFD minor faults */ #else /* !CONFIG_HAVE_ARCH_USERFAULTFD_MINOR */ # define VM_UFFD_MINOR VM_NONE _ Patches currently in -mm which might be from revest@chromium.org are