linux-stable.git/drivers/char/mem.c, branch linux-3.12.y

mm: Tighten x86 /dev/mem with zeroing reads

2017-05-09T06:19:26+00:00

commit a4866aa812518ed1a37d8ea0c881dc946409de94 upstream.

Under CONFIG_STRICT_DEVMEM, reading System RAM through /dev/mem is
disallowed. However, on x86, the first 1MB was always allowed for BIOS
and similar things, regardless of it actually being System RAM. It was
possible for heap to end up getting allocated in low 1MB RAM, and then
read by things like x86info or dd, which would trip hardened usercopy:

usercopy: kernel memory exposure attempt detected from ffff880000090000 (dma-kmalloc-256) (4096 bytes)

This changes the x86 exception for the low 1MB by reading back zeros for
System RAM areas instead of blindly allowing them. More work is needed to
extend this to mmap, but currently mmap doesn't go through usercopy, so
hardened usercopy won't Oops the kernel.

Reported-by: Tommi Rantala 
Tested-by: Tommi Rantala 
Signed-off-by: Kees Cook 
Cc: Brad Spengler 
Signed-off-by: Jiri Slaby

x86/mm/pat, /dev/mem: Remove superfluous error message

2016-09-29T09:14:20+00:00

commit 39380b80d72723282f0ea1d1bbf2294eae45013e upstream.

Currently it's possible for broken (or malicious) userspace to flood a
kernel log indefinitely with messages a-la

	Program dmidecode tried to access /dev/mem between f0000->100000

because range_is_allowed() is case of CONFIG_STRICT_DEVMEM being turned on
dumps this information each and every time devmem_is_allowed() fails.

Reportedly userspace that is able to trigger contignuous flow of these
messages exists.

It would be possible to rate limit this message, but that'd have a
questionable value; the administrator wouldn't get information about all
the failing accessess, so then the information would be both superfluous
and incomplete at the same time :)

Returning EPERM (which is what is actually happening) is enough indication
for userspace what has happened; no need to log this particular error as
some sort of special condition.

Signed-off-by: Jiri Kosina 
Cc: Andrew Morton 
Cc: Andy Lutomirski 
Cc: Borislav Petkov 
Cc: Brian Gerst 
Cc: Denys Vlasenko 
Cc: H. Peter Anvin 
Cc: Josh Poimboeuf 
Cc: Kees Cook 
Cc: Linus Torvalds 
Cc: Luis R. Rodriguez 
Cc: Peter Zijlstra 
Cc: Thomas Gleixner 
Cc: Toshi Kani 
Link: http://lkml.kernel.org/r/alpine.LNX.2.00.1607081137020.24757@cbobk.fhfr.pm
Signed-off-by: Ingo Molnar 
Signed-off-by: Jiri Slaby

/dev/mem: handle out-of-bounds read/write

2014-04-25T16:40:45+00:00

commit 08d2d00b291ed4eb91530050274e67a761c1901d upstream.

The loff_t type may be wider than phys_addr_t (e.g. on 32-bit systems).
Consequently, the file offset may be truncated in the assignment.
Currently, /dev/mem wraps around, which may cause applications to read
or write incorrect regions of memory by accident.

Let's follow POSIX file semantics here and return 0 when reading from
and -EFBIG when writing to an offset that cannot be represented by a
phys_addr_t.

Note that the conditional is optimized out by the compiler if loff_t
has the same size as phys_addr_t.

Signed-off-by: Petr Tesarik 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Jiri Slaby

/dev/oldmem: Remove the interface

2013-07-03T23:08:03+00:00

/dev/oldmem provides the interface for us to access the "old memory" in
the dump-capture kernel.  Unfortunately, no one actually uses this
interface.

And this interface could actually cause some real problems if used on ia64
where the cached/uncached accesses are mixed.  See the discussion from the
link: https://lkml.org/lkml/2013/4/12/386.

So Eric suggested that we should remove /dev/oldmem as an unused piece of
code.

[akpm@linux-foundation.org: mention /dev/oldmem obsolescence in devices.txt]
Suggested-by: "Eric W. Biederman" 
Signed-off-by: Zhang Yanfei 
Cc: Vivek Goyal 
Cc: Dave Hansen 
Cc: "H. Peter Anvin" 
Cc: "H. Peter Anvin" 
Cc: Benjamin Herrenschmidt 
Cc: Fenghua Yu 
Cc: Heiko Carstens 
Cc: Martin Schwidefsky 
Cc: Matt Fleming 
Cc: Michael Holzheu 
Cc: Paul Mackerras 
Cc: Ralf Baechle 
Cc: Tony Luck 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

drivers: char: mem: use IS_ERR_VALUE() in memory_lseek()

2013-06-06T19:54:08+00:00

Use IS_ERR_VALUE() instead of comparing the new offset to a hard-coded
value of -MAX_ERRNO (which is also off-by-one due to the use of ~
instead of -).

Signed-off-by: Rasmus Villemoes 
Signed-off-by: Greg Kroah-Hartman

aio: don't include aio.h in sched.h

2013-05-08T03:16:25+00:00

Faster kernel compiles by way of fewer unnecessary includes.

[akpm@linux-foundation.org: fix fallout]
[akpm@linux-foundation.org: fix build]
Signed-off-by: Kent Overstreet 
Cc: Zach Brown 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Mark Fasheh 
Cc: Joel Becker 
Cc: Rusty Russell 
Cc: Jens Axboe 
Cc: Asai Thambi S P 
Cc: Selvan Mani 
Cc: Sam Bradshaw 
Cc: Jeff Moyer 
Cc: Al Viro 
Cc: Benjamin LaHaise 
Reviewed-by: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

char: add aio_{read,write} to /dev/{null,zero}

2013-05-08T01:38:28+00:00

These are handy for measuring the cost of the aio infrastructure with
operations that do very little and complete immediately.

Signed-off-by: Zach Brown 
Signed-off-by: Kent Overstreet 
Cc: Felipe Balbi 
Cc: Greg Kroah-Hartman 
Cc: Mark Fasheh 
Cc: Joel Becker 
Cc: Rusty Russell 
Cc: Jens Axboe 
Cc: Asai Thambi S P 
Cc: Selvan Mani 
Cc: Sam Bradshaw 
Acked-by: Jeff Moyer 
Cc: Al Viro 
Cc: Benjamin LaHaise 
Reviewed-by: "Theodore Ts'o" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

2013-02-27T04:16:07+00:00

Pull vfs pile (part one) from Al Viro:
 "Assorted stuff - cleaning namei.c up a bit, fixing ->d_name/->d_parent
  locking violations, etc.

  The most visible changes here are death of FS_REVAL_DOT (replaced with
  "has ->d_weak_revalidate()") and a new helper getting from struct file
  to inode.  Some bits of preparation to xattr method interface changes.

  Misc patches by various people sent this cycle *and* ocfs2 fixes from
  several cycles ago that should've been upstream right then.

  PS: the next vfs pile will be xattr stuff."

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (46 commits)
  saner proc_get_inode() calling conventions
  proc: avoid extra pde_put() in proc_fill_super()
  fs: change return values from -EACCES to -EPERM
  fs/exec.c: make bprm_mm_init() static
  ocfs2/dlm: use GFP_ATOMIC inside a spin_lock
  ocfs2: fix possible use-after-free with AIO
  ocfs2: Fix oops in ocfs2_fast_symlink_readpage() code path
  get_empty_filp()/alloc_file() leave both ->f_pos and ->f_version zero
  target: writev() on single-element vector is pointless
  export kernel_write(), convert open-coded instances
  fs: encode_fh: return FILEID_INVALID if invalid fid_type
  kill f_vfsmnt
  vfs: kill FS_REVAL_DOT by adding a d_weak_revalidate dentry op
  nfsd: handle vfs_getattr errors in acl protocol
  switch vfs_getattr() to struct path
  default SET_PERSONALITY() in linux/elf.h
  ceph: prepopulate inodes only when request is aborted
  d_hash_and_lookup(): export, switch open-coded instances
  9p: switch v9fs_set_create_acl() to inode+fid, do it before d_instantiate()
  9p: split dropping the acls from v9fs_set_create_acl()
  ...

new helper: file_inode(file)

2013-02-23T04:31:31+00:00

Signed-off-by: Al Viro

drivers/char/mem.c: fix small coding style issues

2013-02-06T19:21:51+00:00

This patch fixes four foo * bar errors, and one trailing whitespace
complaint from checkpatch.pl

Signed-off-by: Hans Grob 
Signed-off-by: Greg Kroah-Hartman