From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AE18C433F5 for ; Tue, 16 Nov 2021 19:42:40 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B08B63215 for ; Tue, 16 Nov 2021 19:42:40 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240113AbhKPTpg (ORCPT ); Tue, 16 Nov 2021 14:45:36 -0500 Received: from smtp-relay-canonical-1.canonical.com ([185.125.188.121]:45300 "EHLO smtp-relay-canonical-1.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S239957AbhKPTpe (ORCPT ); Tue, 16 Nov 2021 14:45:34 -0500 Received: from mussarela.. (201-43-193-232.dsl.telesp.net.br [201.43.193.232]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-canonical-1.canonical.com (Postfix) with ESMTPSA id 133DE3F1CB; Tue, 16 Nov 2021 19:42:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1637091756; bh=GupNkilR37VWVbjHttHkCvmnjtw2i6j40zM4iiXRUZQ=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=D1Y9VCpBvV8tHG/UxVf32nHZWq1z/0XgtHfhUSDPonVrxa8F3xUC4wPfuCtPjgiio BH2wiYl9GLYufWiFw36Zc1zRXPT05iZERfderXhM+83xm9EqU+TwsBmRMraJ9SxVNX OydqHKE99uuKv04zDt9zJbpzg1ItDjWYNLDlKdmzohPS4ujKIAXM1teQ+l0HkRvnhk +NVFl7oG9g2BBzmFZAXYeB3iwyvS0iKJG9NXA6y1m2WXjdDLmgCxXGlNA3Ky/6eDkd OmRxRkKzzVVNBGBF0nALB7AW9QoxB97I6MePkxM4jYPeuioejDM4ZeZCJAEmBY1Vvr XwiDlxljMP3lg== From: Thadeu Lima de Souza Cascardo To: kernel-team@lists.ubuntu.com Cc: "Matthew Wilcox (Oracle)" , Hao Sun , Kees Cook , Christian Brauner , Al Viro , Mimi Zohar , stable@vger.kernel.org, Andrew Morton , Linus Torvalds , Thadeu Lima de Souza Cascardo Subject: [SRU Hirsute/Impish] vfs: check fd has read access in kernel_read_file_from_fd() Date: Tue, 16 Nov 2021 16:42:16 -0300 Message-Id: <20211116194217.481966-2-cascardo@canonical.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211116194217.481966-1-cascardo@canonical.com> References: <20211116194217.481966-1-cascardo@canonical.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: "Matthew Wilcox (Oracle)" BugLink: https://bugs.launchpad.net/bugs/1950644 If we open a file without read access and then pass the fd to a syscall whose implementation calls kernel_read_file_from_fd(), we get a warning from __kernel_read(): if (WARN_ON_ONCE(!(file->f_mode & FMODE_READ))) This currently affects both finit_module() and kexec_file_load(), but it could affect other syscalls in the future. Link: https://lkml.kernel.org/r/20211007220110.600005-1-willy@infradead.org Fixes: b844f0ecbc56 ("vfs: define kernel_copy_file_from_fd()") Signed-off-by: Matthew Wilcox (Oracle) Reported-by: Hao Sun Reviewed-by: Kees Cook Acked-by: Christian Brauner Cc: Al Viro Cc: Mimi Zohar Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds (cherry picked from commit 032146cda85566abcd1c4884d9d23e4e30a07e9a) Signed-off-by: Thadeu Lima de Souza Cascardo --- fs/kernel_read_file.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/kernel_read_file.c b/fs/kernel_read_file.c index 90d255fbdd9b..c84d87f558cb 100644 --- a/fs/kernel_read_file.c +++ b/fs/kernel_read_file.c @@ -178,7 +178,7 @@ int kernel_read_file_from_fd(int fd, loff_t offset, void **buf, struct fd f = fdget(fd); int ret = -EBADF; - if (!f.file) + if (!f.file || !(f.file->f_mode & FMODE_READ)) goto out; ret = kernel_read_file(f.file, offset, buf, buf_size, file_size, id); -- 2.32.0