From mboxrd@z Thu Jan 1 00:00:00 1970 From: Tyler Hicks Subject: [PATCH] eCryptfs: infinite loop due to overflow in ecryptfs_write() Date: Thu, 19 Jan 2012 03:13:33 -0600 Message-ID: <1326964413-8529-1-git-send-email-tyhicks@canonical.com> References: <12011909443668a7a65ff897afc93db177848236f08f@nudt.edu.cn> Cc: ecryptfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Cong Wang , Yunchuan Wen To: Li Wang Return-path: In-Reply-To: <12011909443668a7a65ff897afc93db177848236f08f@nudt.edu.cn> Sender: ecryptfs-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org From: Li Wang ecryptfs_write() can enter an infinite loop when truncating a file to a size larger than 4G. This only happens on architectures where size_t is represented by 32 bits. This was caused by a size_t overflow due to it incorrectly being used to store the result of a calculation which uses potentially large values of type loff_t. [tyhicks@canonical.com: rewrite subject and commit message] Signed-off-by: Li Wang Signed-off-by: Yunchuan Wen Cc: Cong Wang Cc: Signed-off-by: Tyler Hicks --- fs/ecryptfs/read_write.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-) diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 3745f7c..ec3d936 100644 --- a/fs/ecryptfs/read_write.c +++ b/fs/ecryptfs/read_write.c @@ -130,13 +130,13 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, pgoff_t ecryptfs_page_idx = (pos >> PAGE_CACHE_SHIFT); size_t start_offset_in_page = (pos & ~PAGE_CACHE_MASK); size_t num_bytes = (PAGE_CACHE_SIZE - start_offset_in_page); - size_t total_remaining_bytes = ((offset + size) - pos); + loff_t total_remaining_bytes = ((offset + size) - pos); if (num_bytes > total_remaining_bytes) num_bytes = total_remaining_bytes; if (pos < offset) { /* remaining zeros to write, up to destination offset */ - size_t total_remaining_zeros = (offset - pos); + loff_t total_remaining_zeros = (offset - pos); if (num_bytes > total_remaining_zeros) num_bytes = total_remaining_zeros; -- 1.7.8.3