From: Li Wang Date: Thu, 19 Jan 2012 01:44:36 +0000 (+0800) Subject: eCryptfs: Infinite loop due to overflow in ecryptfs_write() X-Git-Tag: firefly_0821_release~7541^2~1782 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=1a11d5d7fb7988a92e798dfbed7cdd350c0701cc;p=firefly-linux-kernel-4.4.55.git eCryptfs: Infinite loop due to overflow in ecryptfs_write() commit 684a3ff7e69acc7c678d1a1394fe9e757993fd34 upstream. 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 Reviewed-by: Cong Wang Signed-off-by: Tyler Hicks Signed-off-by: Greg Kroah-Hartman --- diff --git a/fs/ecryptfs/read_write.c b/fs/ecryptfs/read_write.c index 54eb14caad7b..608c1c3fde1b 100644 --- a/fs/ecryptfs/read_write.c +++ b/fs/ecryptfs/read_write.c @@ -130,7 +130,7 @@ 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 (fatal_signal_pending(current)) { rc = -EINTR; @@ -141,7 +141,7 @@ int ecryptfs_write(struct inode *ecryptfs_inode, char *data, loff_t offset, 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;