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authorDan Williams <dan.j.williams@intel.com>2018-01-29 17:03:05 -0800
committerThomas Gleixner <tglx@linutronix.de>2018-01-30 21:54:32 +0100
commit56c30ba7b348b90484969054d561f711ba196507 (patch)
tree6e5d8ed79763c5cbf8477f8627ae0545dacc3ff0 /include/linux/fdtable.h
parent2fbd7af5af8665d18bcefae3e9700be07e22b681 (diff)
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.reshetova@intel.com> Signed-off-by: Dan Williams <dan.j.williams@intel.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Cc: linux-arch@vger.kernel.org Cc: kernel-hardening@lists.openwall.com Cc: gregkh@linuxfoundation.org Cc: Al Viro <viro@zeniv.linux.org.uk> Cc: torvalds@linux-foundation.org Cc: alan@linux.intel.com Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com
Diffstat (limited to 'include/linux/fdtable.h')
-rw-r--r--include/linux/fdtable.h5
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h
index 1c65817673db..41615f38bcff 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;
}