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Message-Id: <1519382538-15143-17-git-send-email-jinpu.wangl@profitbricks.com>
Date: Fri, 23 Feb 2018 11:42:05 +0100
From: Jack Wang <jinpu.wang@...fitbricks.com>
To: gregkh@...uxfoundation.org,
stable@...r.kernel.org
Cc: Dan Williams <dan.j.williams@...el.com>,
Thomas Gleixner <tglx@...utronix.de>,
linux-arch@...r.kernel.org,
kernel-hardening@...ts.openwall.com,
Al Viro <viro@...iv.linux.org.uk>,
torvalds@...ux-foundation.org,
alan@...ux.intel.com,
David Woodhouse <dwmw@...zon.co.uk>,
Jack Wang <jinpu.wang@...fitbricks.com>
Subject: [stable 4.4 16/29] vfs, fdtable: Prevent bounds-check bypass via speculative execution
From: Dan Williams <dan.j.williams@...el.com>
(cherry picked from 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.
Co-developed-by: Elena Reshetova <elena.reshetova@...el.com>
Signed-off-by: Dan Williams <dan.j.williams@...el.com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Cc: linux-arch@...r.kernel.org
Cc: kernel-hardening@...ts.openwall.com
Cc: gregkh@...uxfoundation.org
Cc: Al Viro <viro@...iv.linux.org.uk>
Cc: torvalds@...ux-foundation.org
Cc: alan@...ux.intel.com
Link: https://lkml.kernel.org/r/151727418500.33451.17392199002892248656.stgit@dwillia2-desk3.amr.corp.intel.com
Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[jwang: cherry pick to 4.4]
Signed-off-by: Jack Wang <jinpu.wang@...fitbricks.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 5295535..a7b7a05 100644
--- a/include/linux/fdtable.h
+++ b/include/linux/fdtable.h
@@ -9,6 +9,7 @@
#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>
@@ -81,8 +82,10 @@ 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;
}
--
2.7.4
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