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 98F0D125AE for ; Thu, 24 Aug 2023 15:02:38 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 1B179C433C8; Thu, 24 Aug 2023 15:02:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1692889358; bh=PhZJsjBzRZbfyiK2Z+IAXDRAjWUefcarXFlvqx9qENY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IsMmJJRoDP7rFKJ+3zHkRiBcnvBXYfz4T1aD1ZPeamn5vG7C2/xAW9J2CXVc/haf/ NdQ4hNBEANwQS4kRBDqj3nI1f2npP4AtwxSviCQJSYu8o0NA2rSclxjhC4mn5hQ+jH gNQFPKNE8pT+AYRDszH2FDiPqX9X3mtFkjgat4uM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Chen Lifu , Ben Dooks , Palmer Dabbelt , Sasha Levin Subject: [PATCH 5.10 107/135] riscv: lib: uaccess: fix CSR_STATUS SR_SUM bit Date: Thu, 24 Aug 2023 16:50:50 +0200 Message-ID: <20230824145031.575712293@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230824145027.008282920@linuxfoundation.org> References: <20230824145027.008282920@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Chen Lifu [ Upstream commit c08b4848f596fd95543197463b5162bd7bab2442 ] Since commit 5d8544e2d007 ("RISC-V: Generic library routines and assembly") and commit ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code"), if __clear_user and __copy_user return from an fixup branch, CSR_STATUS SR_SUM bit will be set, it is a vulnerability, so that S-mode memory accesses to pages that are accessible by U-mode will success. Disable S-mode access to U-mode memory should clear SR_SUM bit. Fixes: 5d8544e2d007 ("RISC-V: Generic library routines and assembly") Fixes: ebcbd75e3962 ("riscv: Fix the bug in memory access fixup code") Signed-off-by: Chen Lifu Reviewed-by: Ben Dooks Link: https://lore.kernel.org/r/20220615014714.1650349-1-chenlifu@huawei.com Cc: stable@vger.kernel.org Signed-off-by: Palmer Dabbelt Stable-dep-of: 4b05b993900d ("riscv: uaccess: Return the number of bytes effectively not copied") Signed-off-by: Sasha Levin --- arch/riscv/lib/uaccess.S | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/arch/riscv/lib/uaccess.S b/arch/riscv/lib/uaccess.S index baddd6a0d0229..039050172d083 100644 --- a/arch/riscv/lib/uaccess.S +++ b/arch/riscv/lib/uaccess.S @@ -178,7 +178,7 @@ ENTRY(__asm_copy_from_user) /* Exception fixup code */ 10: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, t5 ret ENDPROC(__asm_copy_to_user) @@ -230,7 +230,7 @@ ENTRY(__clear_user) /* Exception fixup code */ 11: /* Disable access to user memory */ - csrs CSR_STATUS, t6 + csrc CSR_STATUS, t6 mv a0, a1 ret ENDPROC(__clear_user) -- 2.40.1