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 C19F64052B3; Wed, 30 Sep 2026 19:32:06 +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=1790796727; cv=none; b=tf3sGHheiHAK1q1GyvMxrpg9F9io68ea6FU5GQDXiZ/opcjH1jEakSkePiiXuJh2lkedLqBv7axvd3yDYARw1Uca+RQ4srt1Lnz5HvxxGZl0ENq0Fb4VzT73Hts339Ot4QELd8RR3vUKWGIQEwb7dVQm4aZAx/BvjO1W5fnWx1I= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790796727; c=relaxed/simple; bh=Cqrse2WUhogrJ9gbDmzEFS1Fhz7VEGdD2AcZyT3PvbQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=r45LCjMIZQiMhsYmo4B4fTEpE96qTBmtkB8ineVUVljNUJ5yeHjW7X/oCFFIns0XwJE0vaHAZz3/op78knRvoI1kpFypEA31ZCCpv/D9CMdEtjfKb5dzElGchb15gctn2Pp6uh3VTMPoANJl6KHzmhOko6wlc587OtJCSDex7+U= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=l/ro8e0H; 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="l/ro8e0H" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 27B4A1F000FF; Wed, 30 Sep 2026 19:32:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1790796726; bh=Eoz7woRX33O3L/vD1Hp5P6ZkvJH6UsvFjcw2EEDt7YE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=l/ro8e0HumjrljnK+3W8OunDb+3nSmni2evvWzcWgj5MM6EzyadyJUcOBdb9N8LhJ fgOF9CKDm6B1goyq39TIH03M1aDvRSph4zUBdNmHzGUxJ0fSRty9IhlOEAf25EWBpL VHjswgyovtL+hMlF1v/x1D0LQfnzXZpToV3YmOh0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Zeng Heng , Catalin Marinas , Will Deacon , Sasha Levin Subject: [PATCH 6.6 0998/1193] arm64: io: Reject non-user protection in ioremap_prot() Date: Wed, 30 Sep 2026 17:28:02 +0200 Message-ID: <20260930152456.412998331@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260930152434.301151190@linuxfoundation.org> References: <20260930152434.301151190@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Zeng Heng [ Upstream commit bb756b11ad63832ebee58caf9e8f9381eaecff9f ] Mapping a stack-top page via /dev/mem with PROT_NONE and then reading that process's /proc//cmdline triggers a spurious WARN in ioremap_prot() through generic_access_phys(): WARNING: ./arch/arm64/include/asm/io.h:275 at generic_access_phys Call trace: generic_access_phys+0x1c8/0x228 (P) __access_remote_vm+0x2b4/0x398 access_remote_vm+0x14/0x30 get_mm_cmdline+0xf8/0x2a0 proc_pid_cmdline_read+0x68/0x120 generic_access_phys() passes the protection derived from the user PTE to ioremap_prot(). On arm64, a PROT_NONE mapping is represented by a present-invalid PTE, so pte_present() still returns true and the protection reaches ioremap_prot(). A PROT_NONE mapping does not have PTE_USER, causing the existing WARN_ON_ONCE() in ioremap_prot() to fire even though this is a valid user mapping. Execute-only mappings have the same issue and must not be readable through this path either. ioremap_prot() should therefore reject protection values without PTE_USER without warning. This makes the access fail cleanly for PROT_NONE and execute-only mappings while retaining the existing user-protection contract. Fixes: 8f098037139b ("arm64: io: Extract user memory type in ioremap_prot()") Signed-off-by: Zeng Heng Reviewed-by: Catalin Marinas Signed-off-by: Will Deacon Signed-off-by: Sasha Levin --- arch/arm64/include/asm/io.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/arch/arm64/include/asm/io.h b/arch/arm64/include/asm/io.h index 8fae8746eb98d..806f4e34c7574 100644 --- a/arch/arm64/include/asm/io.h +++ b/arch/arm64/include/asm/io.h @@ -147,7 +147,8 @@ static inline void __iomem *ioremap_prot(phys_addr_t phys, size_t size, pgprot_t prot; pteval_t user_prot_val = pgprot_val(__pgprot(user_prot)); - if (WARN_ON_ONCE(!(user_prot_val & PTE_USER))) + /* Reject PROT_NONE and exec-only */ + if (!(user_prot_val & PTE_USER)) return NULL; prot = __pgprot_modify(PAGE_KERNEL, PTE_ATTRINDX_MASK, -- 2.53.0