Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753775AbbLLUKW (ORCPT ); Sat, 12 Dec 2015 15:10:22 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:36046 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753713AbbLLUHx (ORCPT ); Sat, 12 Dec 2015 15:07:53 -0500 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, David Sterba , Chris Mason Subject: [PATCH 4.2 46/61] btrfs: fix signed overflows in btrfs_sync_file Date: Sat, 12 Dec 2015 12:06:14 -0800 Message-Id: <20151212200459.429386564@linuxfoundation.org> X-Mailer: git-send-email 2.6.4 In-Reply-To: <20151212200457.170255093@linuxfoundation.org> References: <20151212200457.170255093@linuxfoundation.org> User-Agent: quilt/0.64 MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-15 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2060 Lines: 72 4.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: David Sterba commit 9dcbeed4d7e11e1dcf5e55475de3754f0855d1c2 upstream. The calculation of range length in btrfs_sync_file leads to signed overflow. This was caught by PaX gcc SIZE_OVERFLOW plugin. https://forums.grsecurity.net/viewtopic.php?f=1&t=4284 The fsync call passes 0 and LLONG_MAX, the range length does not fit to loff_t and overflows, but the value is converted to u64 so it silently works as expected. The minimal fix is a typecast to u64, switching functions to take (start, end) instead of (start, len) would be more intrusive. Coccinelle script found that there's one more opencoded calculation of the length. @@ loff_t start, end; @@ * end - start Signed-off-by: David Sterba Signed-off-by: Chris Mason Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/file.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) --- a/fs/btrfs/file.c +++ b/fs/btrfs/file.c @@ -1876,8 +1876,13 @@ int btrfs_sync_file(struct file *file, l struct btrfs_log_ctx ctx; int ret = 0; bool full_sync = 0; - const u64 len = end - start + 1; + u64 len; + /* + * The range length can be represented by u64, we have to do the typecasts + * to avoid signed overflow if it's [0, LLONG_MAX] eg. from fsync() + */ + len = (u64)end - (u64)start + 1; trace_btrfs_sync_file(file, datasync); /* @@ -2065,8 +2070,7 @@ int btrfs_sync_file(struct file *file, l } } if (!full_sync) { - ret = btrfs_wait_ordered_range(inode, start, - end - start + 1); + ret = btrfs_wait_ordered_range(inode, start, len); if (ret) { btrfs_end_transaction(trans, root); goto out; -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/