What happens is that a write to /dev/sg is given a request with non-zero
->iovec_count combined with zero ->dxfer_len.  Or with ->dxferp pointing
to an array full of empty iovecs.

Having write permission to /dev/sg shouldn't be equivalent to the
ability to trigger BUG_ON() while holding spinlocks...

Found by Dmitry Vyukov and syzkaller.

[ The BUG_ON() got changed to a WARN_ON_ONCE(), but this fixes the
  underlying issue.  - Linus ]

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Cc: stable@vger.kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Don't crash the machine just because of an empty transfer. Use WARN_ON()
combined with returning an error.

Found by Dmitry Vyukov and syzkaller.

[ Changed to "WARN_ON_ONCE()". Al has a patch that should fix the root
  cause, but a BUG_ON() is not acceptable in any case, and a WARN_ON()
  might still be a cause of excessive log spamming.

  NOTE! If this warning ever triggers, we may end up leaking resources,
  since this doesn't bother to try to clean the command up. So this
  WARN_ON_ONCE() triggering does imply real problems. But BUG_ON() is
  much worse.

  People really need to stop using BUG_ON() for "this shouldn't ever
  happen". It makes pretty much any bug worse.     - Linus ]

Signed-off-by: Johannes Thumshirn <jthumshirn@suse.de>
Reported-by: Dmitry Vyukov <dvyukov@google.com>
Cc: James Bottomley <jejb@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

If ip6_dst_lookup_tail has acquired a dst and fails the IPv4-mapped
check, release the dst before returning an error.

Fixes: ec5e3b0a1d41 ("ipv6: Inhibit IPv4-mapped src address on the wire.")
Signed-off-by: Willem de Bruijn <willemb@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

Pull ARM SoC fixes from Arnd Bergmann:
 "Two more bugfixes that came in during this week:

   - a defconfig change to enable a vital driver used on some Qualcomm
     based phones. This was already queued for 4.11, but the maintainer
     asked to have it in 4.10 after all.

   - a regression fix for the reset controller framework, this got
     broken by a typo in the 4.10 merge window"

* tag 'fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/arm/arm-soc:
  ARM: multi_v7_defconfig: enable Qualcomm RPMCC
  reset: fix shared reset triggered_count decrement on error

Pull ARM fixes from Russell King:
 "A couple of fixes from Kees concerning problems he spotted with our
  user access support"

* 'fixes' of git://git.armlinux.org.uk/~rmk/linux-arm:
  ARM: 8658/1: uaccess: fix zeroing of 64-bit get_user()
  ARM: 8657/1: uaccess: consistently check object sizes

Pull x86 fix from Thomas Gleixner:
 "Make the build clean by working around yet another GCC stupidity"

* 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  x86/vm86: Fix unused variable warning if THP is disabled

Pull locking fix from Thomas Gleixner:
 "Move the futex init function to core initcall so user mode helper does
  not run into an uninitialized futex syscall"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  futex: Move futex_init() to core_initcall

Pull timer fixes from Thomas Gleixner:
 "Two small fixes::

   - Prevent deadlock on the tick broadcast lock. Found and fixed by
     Mike.

   - Stop using printk() in the timekeeping debug code to prevent a
     deadlock against the scheduler"

* 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  timekeeping: Use deferred printk() in debug code
  tick/broadcast: Prevent deadlock on tick_broadcast_lock

Pull networking fixes from David Miller:

 1) Fix leak in dpaa_eth error paths, from Dan Carpenter.

 2) Use after free when using IPV6_RECVPKTINFO, from Andrey Konovalov.

 3) fanout_release() cannot be invoked from atomic contexts, from Anoob
    Soman.

 4) Fix bogus attempt at lockdep annotation in IRDA.

 5) dev_fill_metadata_dst() can OOP on a NULL dst cache pointer, from
    Paolo Abeni.

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net:
  irda: Fix lockdep annotations in hashbin_delete().
  vxlan: fix oops in dev_fill_metadata_dst
  dccp: fix freeing skb too early for IPV6_RECVPKTINFO
  dpaa_eth: small leak on error
  packet: Do not call fanout_release from atomic contexts