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 E70441DC98B; Thu, 3 Jul 2025 14:48:38 +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=1751554120; cv=none; b=SFxPGqKXbaY9hBhuPyoxEqOrr354dFv2UsXo0zD4nwQXrJ1Y2CHrO/B1l9i63ULJiR2qKwc+psaftzzLGF90GFlYg/u1ejTqu8UzQr+3PwfGhUu7zZuuKryCy4XJ+goMqeO2jNnEaG91BGytMc0F5AwUOB2V37s1MplRHDxj3II= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1751554120; c=relaxed/simple; bh=TTdqEXVBEhrcmXf4N0CYJwgYpwsRKwWK9B6FZIVomew=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=V26817K/uGDqH4N/T4GafBWygWI9iVTtEOvYi8vIfb0tmB3fUTbExS4Ll8qg5hQNNVxGXIbzr/MBuLz2uh2KfvI/TzE95jePEy5cBL/bim3DoA1rbdMMKemvlFQ/WHjY9DCHCRnuncXmySNZA7SUaQTcA01jSYkQhXRoQJFTaoU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=TtRqQcT0; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="TtRqQcT0" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 47A36C4CEE3; Thu, 3 Jul 2025 14:48:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1751554118; bh=TTdqEXVBEhrcmXf4N0CYJwgYpwsRKwWK9B6FZIVomew=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=TtRqQcT0N3A9uiWUPggMS5TyGxUJBkGQZ1Oe2h15VHBdv1g1QWBiwmbCoV7IdprQ4 8hHzGxt0UIGDti4CjXDkmF+wxo8pc80AHplWz2tDBnu1uRrtZRVKX0O7rldK/6zup6 16fbCIScxXC1Tmf8cpR2ww31qVgeh94g0iPHmBIE= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, rtm@csail.mit.edu, Nam Cao , Alexandre Ghiti , Palmer Dabbelt Subject: [PATCH 6.12 086/218] Revert "riscv: Define TASK_SIZE_MAX for __access_ok()" Date: Thu, 3 Jul 2025 16:40:34 +0200 Message-ID: <20250703143959.381217768@linuxfoundation.org> X-Mailer: git-send-email 2.50.0 In-Reply-To: <20250703143955.956569535@linuxfoundation.org> References: <20250703143955.956569535@linuxfoundation.org> User-Agent: quilt/0.68 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 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Nam Cao commit 890ba5be6335dbbbc99af14ea007befb5f83f174 upstream. This reverts commit ad5643cf2f69 ("riscv: Define TASK_SIZE_MAX for __access_ok()"). This commit changes TASK_SIZE_MAX to be LONG_MAX to optimize access_ok(), because the previous TASK_SIZE_MAX (default to TASK_SIZE) requires some computation. The reasoning was that all user addresses are less than LONG_MAX, and all kernel addresses are greater than LONG_MAX. Therefore access_ok() can filter kernel addresses. Addresses between TASK_SIZE and LONG_MAX are not valid user addresses, but access_ok() let them pass. That was thought to be okay, because they are not valid addresses at hardware level. Unfortunately, one case is missed: get_user_pages_fast() happily accepts addresses between TASK_SIZE and LONG_MAX. futex(), for instance, uses get_user_pages_fast(). This causes the problem reported by Robert [1]. Therefore, revert this commit. TASK_SIZE_MAX is changed to the default: TASK_SIZE. This unfortunately reduces performance, because TASK_SIZE is more expensive to compute compared to LONG_MAX. But correctness first, we can think about optimization later, if required. Reported-by: Closes: https://lore.kernel.org/linux-riscv/77605.1750245028@localhost/ Signed-off-by: Nam Cao Cc: stable@vger.kernel.org Reviewed-by: Alexandre Ghiti Fixes: ad5643cf2f69 ("riscv: Define TASK_SIZE_MAX for __access_ok()") Link: https://lore.kernel.org/r/20250619155858.1249789-1-namcao@linutronix.de Signed-off-by: Palmer Dabbelt Signed-off-by: Greg Kroah-Hartman --- arch/riscv/include/asm/pgtable.h | 1 - 1 file changed, 1 deletion(-) --- a/arch/riscv/include/asm/pgtable.h +++ b/arch/riscv/include/asm/pgtable.h @@ -916,7 +916,6 @@ static inline pte_t pte_swp_clear_exclus */ #ifdef CONFIG_64BIT #define TASK_SIZE_64 (PGDIR_SIZE * PTRS_PER_PGD / 2) -#define TASK_SIZE_MAX LONG_MAX #ifdef CONFIG_COMPAT #define TASK_SIZE_32 (_AC(0x80000000, UL) - PAGE_SIZE)