Commit-ID: 56c30ba7b348b90484969054d561f711ba196507 Gitweb: https://git.kernel.org/tip/56c30ba7b348b90484969054d561f711ba196507 Author: Dan Williams <dan.j.willi...@intel.com> AuthorDate: Mon, 29 Jan 2018 17:03:05 -0800 Committer: Thomas Gleixner <t...@linutronix.de> CommitDate: Tue, 30 Jan 2018 21:54:32 +0100
vfs, fdtable: Prevent bounds-check bypass via speculative execution 'fd' is a user controlled value that is used as a data dependency to read from the 'fdt->fd' array. In order to avoid potential leaks of kernel memory values, block speculative execution of the instruction stream that could issue reads based on an invalid 'file *' returned from __fcheck_files. Co-developed-by: Elena Reshetova <elena.reshet...@intel.com> Signed-off-by: Dan Williams <dan.j.willi...@intel.com> Signed-off-by: Thomas Gleixner <t...@linutronix.de> Cc: linux-a...@vger.kernel.org Cc: kernel-harden...@lists.openwall.com Cc: gre...@linuxfoundation.org Cc: Al Viro <v...@zeniv.linux.org.uk> Cc: torva...@linux-foundation.org Cc: a...@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.st...@dwillia2-desk3.amr.corp.intel.com --- include/linux/fdtable.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 1c65817..41615f3 100644 --- a/include/linux/fdtable.h +++ b/include/linux/fdtable.h @@ -10,6 +10,7 @@ #include <linux/compiler.h> #include <linux/spinlock.h> #include <linux/rcupdate.h> +#include <linux/nospec.h> #include <linux/types.h> #include <linux/init.h> #include <linux/fs.h> @@ -82,8 +83,10 @@ static inline struct file *__fcheck_files(struct files_struct *files, unsigned i { struct fdtable *fdt = rcu_dereference_raw(files->fdt); - if (fd < fdt->max_fds) + if (fd < fdt->max_fds) { + fd = array_index_nospec(fd, fdt->max_fds); return rcu_dereference_raw(fdt->fd[fd]); + } return NULL; }
