linux-stable.git/include/linux, branch v3.2.40

exec: use -ELOOP for max recursion depth

2013-03-06T03:24:28+00:00

commit d740269867021faf4ce38a449353d2b986c34a67 upstream.

To avoid an explosion of request_module calls on a chain of abusive
scripts, fail maximum recursion with -ELOOP instead of -ENOEXEC. As soon
as maximum recursion depth is hit, the error will fail all the way back
up the chain, aborting immediately.

This also has the side-effect of stopping the user's shell from attempting
to reexecute the top-level file as a shell script. As seen in the
dash source:

        if (cmd != path_bshell && errno == ENOEXEC) {
                *argv-- = cmd;
                *argv = cmd = path_bshell;
                goto repeat;
        }

The above logic was designed for running scripts automatically that lacked
the "#!" header, not to re-try failed recursion. On a legitimate -ENOEXEC,
things continue to behave as the shell expects.

Additionally, when tracking recursion, the binfmt handlers should not be
involved. The recursion being tracked is the depth of calls through
search_binary_handler(), so that function should be exclusively responsible
for tracking the depth.

Signed-off-by: Kees Cook 
Cc: halfdog 
Cc: P J P 
Cc: Alexander Viro 
Signed-off-by: Andrew Morton 
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings

usermodehelper: implement UMH_KILLABLE

2013-03-06T03:24:27+00:00

commit d0bd587a80960d7ba7e0c8396e154028c9045c54 upstream.

Implement UMH_KILLABLE, should be used along with UMH_WAIT_EXEC/PROC.
The caller must ensure that subprocess_info->path/etc can not go away
until call_usermodehelper_freeinfo().

call_usermodehelper_exec(UMH_KILLABLE) does
wait_for_completion_killable.  If it fails, it uses
xchg(&sub_info->complete, NULL) to serialize with umh_complete() which
does the same xhcg() to access sub_info->complete.

If call_usermodehelper_exec wins, it can safely return.  umh_complete()
should get NULL and call call_usermodehelper_freeinfo().

Otherwise we know that umh_complete() was already called, in this case
call_usermodehelper_exec() falls back to wait_for_completion() which
should succeed "very soon".

Note: UMH_NO_WAIT == -1 but it obviously should not be used with
UMH_KILLABLE.  We delay the neccessary cleanup to simplify the back
porting.

Signed-off-by: Oleg Nesterov 
Cc: Tetsuo Handa 
Cc: Rusty Russell 
Cc: Tejun Heo 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

8250: use correct value for PORT_BRCM_TRUMANAGE

2013-03-06T03:24:25+00:00

When backporting commit ebebd49a8eab ('8250/16?50: Add support for
Broadcom TruManage redirected serial port') I took the next
available port type number for PORT_BRCM_TRUMANAGE (22).

However, the 8250 port type numbers are exposed to userland through
the TIOC{G,S}SERIAL ioctls and so must remain stable.  Redefine
PORT_BRCM_TRUMANAGE as 25, matching mainline as of commit
85f024401bf807.

This leaves port types 22-24 within the valid range for 8250 but not
implemented there.  Change serial8250_verify_port() to specifically
reject these and change serial8250_type() to return "unknown" for them
(though I'm not sure why it would ever see them).

Signed-off-by: Ben Hutchings

pstore: Avoid deadlock in panic and emergency-restart path

2013-03-06T03:24:22+00:00

commit 9f244e9cfd70c7c0f82d3c92ce772ab2a92d9f64 upstream.

[Issue]

When pstore is in panic and emergency-restart paths, it may be blocked
in those paths because it simply takes spin_lock.

This is an example scenario which pstore may hang up in a panic path:

 - cpuA grabs psinfo->buf_lock
 - cpuB panics and calls smp_send_stop
 - smp_send_stop sends IRQ to cpuA
 - after 1 second, cpuB gives up on cpuA and sends an NMI instead
 - cpuA is now in an NMI handler while still holding buf_lock
 - cpuB is deadlocked

This case may happen if a firmware has a bug and
cpuA is stuck talking with it more than one second.

Also, this is a similar scenario in an emergency-restart path:

 - cpuA grabs psinfo->buf_lock and stucks in a firmware
 - cpuB kicks emergency-restart via either sysrq-b or hangcheck timer.
   And then, cpuB is deadlocked by taking psinfo->buf_lock again.

[Solution]

This patch avoids the deadlocking issues in both panic and emergency_restart
paths by introducing a function, is_non_blocking_path(), to check if a cpu
can be blocked in current path.

With this patch, pstore is not blocked even if another cpu has
taken a spin_lock, in those paths by changing from spin_lock_irqsave
to spin_trylock_irqsave.

In addition, according to a comment of emergency_restart() in kernel/sys.c,
spin_lock shouldn't be taken in an emergency_restart path to avoid
deadlock. This patch fits the comment below.


/**
 *      emergency_restart - reboot the system
 *
 *      Without shutting down any hardware or taking any locks
 *      reboot the system.  This is called when we know we are in
 *      trouble so this is our best effort to reboot.  This is
 *      safe to call in interrupt context.
 */
void emergency_restart(void)


Signed-off-by: Seiji Aguchi 
Acked-by: Don Zickus 
Signed-off-by: Tony Luck 
[bwh: Backported to 3.2:
 - Adjust context
 - Add #include ]
Signed-off-by: Ben Hutchings

unbreak automounter support on 64-bit kernel with 32-bit userspace (v2)

2013-03-06T03:24:19+00:00

commit 4f4ffc3a5398ef9bdbb32db04756d7d34e356fcf upstream.

automount-support is broken on the parisc architecture, because the existing
#if list does not include a check for defined(__hppa__). The HPPA (parisc)
architecture is similiar to other 64bit Linux targets where we have to define
autofs_wqt_t (which is passed back and forth to user space) as int type which
has a size of 32bit across 32 and 64bit kernels.

During the discussion on the mailing list, H. Peter Anvin suggested to invert
the #if list since only specific platforms (specifically those who do not have
a 32bit userspace, like IA64 and Alpha) should have autofs_wqt_t as unsigned
long type.

This suggestion is probably the best way to go, since Arm64 (and maybe others?)
seems to have a non-working automounter. So in the long run even for other new
upcoming architectures this inverted check seem to be the best solution, since
it will not require them to change this #if again (unless they are 64bit only).

Signed-off-by: Helge Deller 
Acked-by: H. Peter Anvin 
Acked-by: Ian Kent 
Acked-by: Catalin Marinas 
CC: James Bottomley 
CC: Rolf Eike Beer 
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings

nbd: fsync and kill block device on shutdown

2013-03-06T03:24:17+00:00

commit 3a2d63f87989e01437ba994df5f297528c353d7d upstream.

There are two problems with shutdown in the NBD driver.

1: Receiving the NBD_DISCONNECT ioctl does not sync the filesystem.

   This patch adds the sync operation into __nbd_ioctl()'s
   NBD_DISCONNECT handler.  This is useful because BLKFLSBUF is restricted
   to processes that have CAP_SYS_ADMIN, and the NBD client may not
   possess it (fsync of the block device does not sync the filesystem,
   either).

2: Once we clear the socket we have no guarantee that later reads will
   come from the same backing storage.

   The patch adds calls to kill_bdev() in __nbd_ioctl()'s socket
   clearing code so the page cache is cleaned, lest reads that hit on the
   page cache will return stale data from the previously-accessible disk.

Example:

    # qemu-nbd -r -c/dev/nbd0 /dev/sr0
    # file -s /dev/nbd0
    /dev/stdin: # UDF filesystem data (version 1.5) etc.
    # qemu-nbd -d /dev/nbd0
    # qemu-nbd -r -c/dev/nbd0 /dev/sda
    # file -s /dev/nbd0
    /dev/stdin: # UDF filesystem data (version 1.5) etc.

While /dev/sda has:

    # file -s /dev/sda
    /dev/sda: x86 boot sector; etc.

Signed-off-by: Paolo Bonzini 
Acked-by: Paul Clements 
Cc: Alex Bligh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
[bwh: Backported to 3.2:
 - Adjusted context
 - s/\bnbd\b/lo/
 - Incorporate export of kill_bdev() from commit ff01bb483265
   ('fs: move code out of buffer.c')]
Signed-off-by: Ben Hutchings

mm: mmu_notifier: have mmu_notifiers use a global SRCU so they may safely schedule

2013-03-06T03:24:11+00:00

commit 21a92735f660eaecf69a6f2e777f18463760ec32 upstream.

With an RCU based mmu_notifier implementation, any callout to
mmu_notifier_invalidate_range_{start,end}() or
mmu_notifier_invalidate_page() would not be allowed to call schedule()
as that could potentially allow a modification to the mmu_notifier
structure while it is currently being used.

Since srcu allocs 4 machine words per instance per cpu, we may end up
with memory exhaustion if we use srcu per mm.  So all mms share a global
srcu.  Note that during large mmu_notifier activity exit & unregister
paths might hang for longer periods, but it is tolerable for current
mmu_notifier clients.

Signed-off-by: Sagi Grimberg 
Signed-off-by: Andrea Arcangeli 
Cc: Peter Zijlstra 
Cc: Haggai Eran 
Cc: "Paul E. McKenney" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Ben Hutchings

ALSA: usb: Fix Processing Unit Descriptor parsers

2013-03-06T03:24:08+00:00

commit b531f81b0d70ffbe8d70500512483227cc532608 upstream.

Commit 99fc86450c439039d2ef88d06b222fd51a779176 "ALSA: usb-mixer:
parse descriptors with structs" introduced a set of useful parsers
for descriptors. Unfortunately the parses for the Processing Unit
Descriptor came with a very subtle bug...

Functions uac_processing_unit_iProcessing() and
uac_processing_unit_specific() were indexing the baSourceID array
forgetting the fields before the iProcessing and process-specific
descriptors.

The problem was observed with Sound Blaster Extigy mixer,
where nNrModes in Up/Down-mix Processing Unit Descriptor
was accessed at offset 10 of the descriptor (value 0)
instead of offset 15 (value 7). In result the resulting
control had interesting limit values:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - -1
  Mono: -1 [100%]

Fixed by starting from the bmControls, which was calculated
correctly, instead of baSourceID.

Now the mentioned control is fine:

Simple mixer control 'Channel Routing Mode Select',0
  Capabilities: volume volume-joined penum
  Playback channels: Mono
  Capture channels: Mono
  Limits: 0 - 6
  Mono: 0 [0%]

Signed-off-by: Pawel Moll 
Signed-off-by: Takashi Iwai 
[bwh: Backported to 3.2: adjust filename]
Signed-off-by: Ben Hutchings

pps: Add pps_lookup_dev() function

2013-03-06T03:23:57+00:00

commit 513b032c98b4b9414aa4e9b4a315cb1bf0380101 upstream.

The PPS serial line discipline wants to attach a PPS device to a tty
without changing the tty code to add a struct pps_device * pointer.

Since the number of PPS devices in a typical system is generally very low
(n=1 is by far the most common), it's practical to search the entire list
of allocated pps devices.  (We capture the timestamp before the lookup,
so the timing isn't affected.)

It is a bit ugly that this function, which is part of the in-kernel
PPS API, has to be in pps.c as opposed to kapi,c, but that's not
something that affects users.

Signed-off-by: George Spelvin 
Acked-by: Rodolfo Giometti 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Ben Hutchings

idr: idr_for_each_entry() macro

2013-03-06T03:23:57+00:00

commit 9749f30f1a387070e6e8351f35aeb829eacc3ab6 upstream.

Inspired by the list_for_each_entry() macro

Signed-off-by: Philipp Reisner 
Signed-off-by: Ben Hutchings