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| author | Dan Williams <dan.j.williams@intel.com> | 2018-01-29 17:03:05 -0800 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2018-03-19 18:58:37 +0000 |
| commit | b2fddb5b3cbe2ac7d18e62c9588a6cbee9cd7383 (patch) | |
| tree | 4729193d0c0d734fd331a85c3698b9110787b86b | |
| parent | 429edb965dd15507f143cdd08637b0dbfa282f0e (diff) | |
| download | linux-stable-b2fddb5b3cbe2ac7d18e62c9588a6cbee9cd7383.tar.gz linux-stable-b2fddb5b3cbe2ac7d18e62c9588a6cbee9cd7383.tar.bz2 linux-stable-b2fddb5b3cbe2ac7d18e62c9588a6cbee9cd7383.zip | |
vfs, fdtable: Prevent bounds-check bypass via speculative execution
commit 56c30ba7b348b90484969054d561f711ba196507 upstream.
'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
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
| -rw-r--r-- | include/linux/fdtable.h | 5 |
1 files changed, 4 insertions, 1 deletions
diff --git a/include/linux/fdtable.h b/include/linux/fdtable.h index 82163c4b32c9..5a14de6a6f62 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> @@ -85,8 +86,10 @@ 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) { + fd = array_index_nospec(fd, fdt->max_fds); file = rcu_dereference_check_fdtable(files, fdt->fd[fd]); + } return file; } |