Patch "vfs, fdtable: Prevent bounds-check bypass via speculative execution" has been added to the 4.14-stable tree

This is a note to let you know that I've just added the patch titled

vfs, fdtable: Prevent bounds-check bypass via speculative execution

to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
vfs_fdtable_Prevent_bounds-check_bypass_via_speculative_execution.patch
and it can be found in the queue-4.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

Subject: vfs, fdtable: Prevent bounds-check bypass via speculative execution
From: Dan Williams [email protected]
Date: Mon Jan 29 17:03:05 2018 -0800

From: Dan Williams [email protected]

commit 56c30ba7b348b90484969054d561f711ba196507

'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.

---
 include/linux/fdtable.h |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

@@ -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_file
 {
 	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;
 }
 

Patches currently in stable-queue which might be from [email protected] are

queue-4.14/nl80211_Sanitize_array_index_in_parse_txq_params.patch queue-4.14/vfs_fdtable_Prevent_bounds-check_bypass_via_speculative_execution.patch