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 06F16486647; Sat, 12 Sep 2026 19:13:28 +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=1789240409; cv=none; b=bfB3H5tQ+jBstR3jbI9gKgAPoQYqECDhT1ncatW9nLV1TzX8jLet5w51krLvYmsbnVIneGG5FEdHws8lTiBGhDqfCjHGtIRSDT/ZAQ3nkqkkDkUDY+oT6AXGkAR1KzZD1AqOdIqzN1fDo1T5dJjZV3oy27q8NkfSgCNR6rp3NWA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789240409; c=relaxed/simple; bh=oGBoQvUJDJ4ubyjtATDM7vY8IA4LgXzOqtu+z8O7PFY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=kx1FsX7/sSG5kbr/pG9f/X5iyiFkxzXTV7lQ1/1em76FOsMwZrvx54U+/P/4dVE7nJTbdV63e3Nv0BcQe62jcVOsOa6fF5pK+8B8q0RfdnM0doOVBqyeU8emTaczq928RsUgWlDicX8JGFuxyQb9CE87B5b/GMSlxtODFQq9BG4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=LaVD/YjR; 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="LaVD/YjR" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0C26F1F000FF; Sat, 12 Sep 2026 19:13:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1789240407; bh=DO816y/NFTRDnxhrl/KAjuuczrpeuBcIyjU4Y+vPF+k=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=LaVD/YjRPZl1OxK9dSWEQxeZoD/iR2R5EG/waxixvsVN2r5yM4j9myhtMoqYL4HfV JhtsnneZCQuGE2gnDCk7tfT6ONXXIKJu5l2AaW0j0EmWRFyuFle+Ah5fNg9iYI3le4 r82Sv5/NKSJ3CFBMLGPoB81IOVYP3b+GkJkQskv4= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Bijan Tabatabai , Dave Hansen , Sasha Levin Subject: [PATCH 5.15 819/935] x86/pkeys: Fix pkey_alloc() return value when pkeys are not supported Date: Sat, 12 Sep 2026 09:04:09 +0200 Message-ID: <20260912065545.615445186@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260912065526.833703348@linuxfoundation.org> References: <20260912065526.833703348@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 5.15-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bijan Tabatabai [ Upstream commit dee87e09b0dd63da9b1e1876167ccae37842dfd0 ] The man page for pkey_alloc(2) specifies that it should return -1 with the errno set to ENOSPC when pkeys are not supported [1]. However, on x86 pkey_alloc() sets errno to EINVAL when called for the first time on a CPU that does not support pkeys. The root cause of this is the x86 implementation of mm_pkey_alloc() not directly checking if pkeys are supported. It only checks if all the pkeys have been allocated by comparing the allocation map against all_pkeys_mask. When OSPKE is not enabled, init_new_context() skips the initialization of the allocation map, leaving it as 0, while all_pkeys_mask is 1. mm_pkey_alloc() interprets this as there being a pkey available and it returns pkey 0. Then, pkey_alloc() fails with -EINVAL from arch_set_user_pkey_access() instead of returning -ENOSPC. Subsequent calls to pkey_alloc() do return -ENOSPC because pkey 0 is left marked as allocated. Change mm_pkey_alloc() to directly check if OSPKE is enabled, and return -1 if it is not, which causes pkey_alloc() to return -ENOSPC. The arm64 and powerpc implementations of mm_pkey_alloc() already do this check. [1] https://man7.org/linux/man-pages/man2/pkey_alloc.2.html [ dhansen: use arch_pkeys_enabled() to follow arm ] Fixes: e8c24d3a23a4 ("x86/pkeys: Allocation/free syscalls") Signed-off-by: Bijan Tabatabai Signed-off-by: Dave Hansen Link: https://patch.msgid.link/20260716220604.26452-1-bijan311@gmail.com Signed-off-by: Sasha Levin --- arch/x86/include/asm/pkeys.h | 3 +++ 1 file changed, 3 insertions(+) diff --git a/arch/x86/include/asm/pkeys.h b/arch/x86/include/asm/pkeys.h index 1d5f14aff5f6f..8215664de3f91 100644 --- a/arch/x86/include/asm/pkeys.h +++ b/arch/x86/include/asm/pkeys.h @@ -92,6 +92,9 @@ int mm_pkey_alloc(struct mm_struct *mm) u16 all_pkeys_mask = ((1U << arch_max_pkey()) - 1); int ret; + if (!arch_pkeys_enabled()) + return -1; + /* * Are we out of pkeys? We must handle this specially * because ffz() behavior is undefined if there are no -- 2.53.0