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 78AC21AC896; Thu, 15 Aug 2024 14:19:54 +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=1723731594; cv=none; b=Gx2hX248/wgXT8hf0r0n0PJt9dTG1+bs2qjaoMpM1znd/fgL1f8/4F92lWpJIiHcZYJFfSTKmHUWujHxQa23BDCwuGfaPRS4II7b0uumjnBwXegAW8o/VorED9eTiBct4ezsVQfNmS24DMgFgIZ9KPhBgeGFrFZHj0pkOk8Fm7k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1723731594; c=relaxed/simple; bh=iCxfgtAlR+xJiZuFxkWjVG2RHGPKw/uVPERCweTxjHI=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=uQOkgd2cCbxNZA1YUX6gOBeVCgjYDzQSBwUp0L5fm9PMKlZZpbHHlaibC7kMeBActubhGvf8JJdbw9KgwIWS9FLENlNLvmOMiXSI/TDdqLMiYHz15I+dcEOllwmlzjJ+8Lo5Ac1iSBCcaL0aEZfIwXRK2GUdmksAKBQTcNKWoIw= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=yxCFAlla; 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="yxCFAlla" Received: by smtp.kernel.org (Postfix) with ESMTPSA id E327EC32786; Thu, 15 Aug 2024 14:19:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1723731594; bh=iCxfgtAlR+xJiZuFxkWjVG2RHGPKw/uVPERCweTxjHI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=yxCFAllaAYngUxQOM7QhSS4OpHl5BAyh77nNjpnCqSsybnLjXBUiDfxaA/S4uQiIy wpyUOYak1PUYosKSPWDTQy9ZJyiyK7ihyNmPM9kLycm/jbUtxTrTSUyHrB/02VS3bz 7SAMeN1Estu9c/Bx2ANov3LD5LIbqJZSSTWqMOeY= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Al Viro Subject: [PATCH 5.4 179/259] protect the fetch of ->fd[fd] in do_dup2() from mispredictions Date: Thu, 15 Aug 2024 15:25:12 +0200 Message-ID: <20240815131909.691966354@linuxfoundation.org> X-Mailer: git-send-email 2.46.0 In-Reply-To: <20240815131902.779125794@linuxfoundation.org> References: <20240815131902.779125794@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Al Viro commit 8aa37bde1a7b645816cda8b80df4753ecf172bf1 upstream. both callers have verified that fd is not greater than ->max_fds; however, misprediction might end up with tofree = fdt->fd[fd]; being speculatively executed. That's wrong for the same reasons why it's wrong in close_fd()/file_close_fd_locked(); the same solution applies - array_index_nospec(fd, fdt->max_fds) could differ from fd only in case of speculative execution on mispredicted path. Cc: stable@vger.kernel.org Signed-off-by: Al Viro Signed-off-by: Greg Kroah-Hartman --- fs/file.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/file.c +++ b/fs/file.c @@ -908,6 +908,7 @@ __releases(&files->file_lock) * tables and this condition does not arise without those. */ fdt = files_fdtable(files); + fd = array_index_nospec(fd, fdt->max_fds); tofree = fdt->fd[fd]; if (!tofree && fd_is_open(fd, fdt)) goto Ebusy;