From f64b013cfecb2a5c698f7089daefcf73b093ca22 Mon Sep 17 00:00:00 2001 From: Elena Reshetova Date: Wed, 30 Aug 2017 13:52:22 +0300 Subject: [PATCH 098/131] fs: prevent speculative execution CVE-2017-5753 (Spectre v1 Intel) Since the fd value in function __fcheck_files() seems to be controllable by userspace and later on conditionally (upon bound check) used to resolve fdt->fd, insert an observable speculation barrier before its usage. This should prevent observable speculation on that branch and avoid kernel memory leak. Signed-off-by: Elena Reshetova Signed-off-by: Andy Whitcroft --- include/linux/fdtable.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 085197bd8812..e94d7b45911c 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -79,8 +79,10 @@ static inline struct file * fcheck_files(struct files_struct *files, unsigned in struct file * file = NULL; struct fdtable *fdt = files_fdtable(files); - if (fd < fdt->max_fds) + if (fd < fdt->max_fds) { + osb(); file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); + } return file; } -- 2.15.1