linux-stable.git/include/linux, branch v3.18.30

tracing: Fix check for cpu online when event is disabled

2016-03-22T15:11:16+00:00

[ Upstream commit dc17147de328a74bbdee67c1bf37d2f1992de756 ]

Commit f37755490fe9b ("tracepoints: Do not trace when cpu is offline") added
a check to make sure that tracepoints only get called when the cpu is
online, as it uses rcu_read_lock_sched() for protection.

Commit 3a630178fd5f3 ("tracing: generate RCU warnings even when tracepoints
are disabled") added lockdep checks (including rcu checks) for events that
are not enabled to catch possible RCU issues that would only be triggered if
a trace event was enabled. Commit f37755490fe9b only stopped the warnings
when the trace event was enabled but did not prevent warnings if the trace
event was called when disabled.

To fix this, the cpu online check is moved to where the condition is added
to the trace event. This will place the cpu online check in all places that
it may be used now and in the future.

Cc: stable@vger.kernel.org # v3.18+
Fixes: f37755490fe9b ("tracepoints: Do not trace when cpu is offline")
Fixes: 3a630178fd5f3 ("tracing: generate RCU warnings even when tracepoints are disabled")
Reported-by: Sudeep Holla 
Tested-by: Sudeep Holla 
Signed-off-by: Steven Rostedt 
Signed-off-by: Sasha Levin

block: bio: introduce helpers to get the 1st and last bvec

2016-03-13T17:53:41+00:00

[ Upstream commit 7bcd79ac50d9d83350a835bdb91c04ac9e098412 ]

The bio passed to bio_will_gap() may be fast cloned from upper
layer(dm, md, bcache, fs, ...), or from bio splitting in block
core.

Unfortunately bio_will_gap() just figures out the last bvec via
'bi_io_vec[prev->bi_vcnt - 1]' directly, and this way is obviously
wrong.

This patch introduces two helpers for getting the first and last
bvec of one bio for fixing the issue.

Cc: stable@vger.kernel.org
Reported-by: Sagi Grimberg 
Reviewed-by: Sagi Grimberg 
Reviewed-by: Christoph Hellwig 
Signed-off-by: Ming Lei 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

libata: Align ata_device's id on a cacheline

2016-03-11T14:45:21+00:00

[ Upstream commit 4ee34ea3a12396f35b26d90a094c75db95080baa ]

The id buffer in ata_device is a DMA target, but it isn't explicitly
cacheline aligned. Due to this, adjacent fields can be overwritten with
stale data from memory on non coherent architectures. As a result, the
kernel is sometimes unable to communicate with an ATA device.

Fix this by ensuring that the id buffer is cacheline aligned.

This issue is similar to that fixed by Commit 84bda12af31f
("libata: align ap->sector_buf").

Signed-off-by: Harvey Hunt 
Cc: linux-kernel@vger.kernel.org
Cc:  # 2.6.18
Signed-off-by: Tejun Heo 
Signed-off-by: Sasha Levin

libata: fix HDIO_GET_32BIT ioctl

2016-03-08T02:13:02+00:00

[ Upstream commit 287e6611ab1eac76c2c5ebf6e345e04c80ca9c61 ]

As reported by Soohoon Lee, the HDIO_GET_32BIT ioctl does not
work correctly in compat mode with libata.

I have investigated the issue further and found multiple problems
that all appeared with the same commit that originally introduced
HDIO_GET_32BIT handling in libata back in linux-2.6.8 and presumably
also linux-2.4, as the code uses "copy_to_user(arg, &val, 1)" to copy
a 'long' variable containing either 0 or 1 to user space.

The problems with this are:

* On big-endian machines, this will always write a zero because it
  stores the wrong byte into user space.

* In compat mode, the upper three bytes of the variable are updated
  by the compat_hdio_ioctl() function, but they now contain
  uninitialized stack data.

* The hdparm tool calling this ioctl uses a 'static long' variable
  to store the result. This means at least the upper bytes are
  initialized to zero, but calling another ioctl like HDIO_GET_MULTCOUNT
  would fill them with data that remains stale when the low byte
  is overwritten. Fortunately libata doesn't implement any of the
  affected ioctl commands, so this would only happen when we query
  both an IDE and an ATA device in the same command such as
  "hdparm -N -c /dev/hda /dev/sda"

* The libata code for unknown reasons started using ATA_IOC_GET_IO32
  and ATA_IOC_SET_IO32 as aliases for HDIO_GET_32BIT and HDIO_SET_32BIT,
  while the ioctl commands that were added later use the normal
  HDIO_* names. This is harmless but rather confusing.

This addresses all four issues by changing the code to use put_user()
on an 'unsigned long' variable in HDIO_GET_32BIT, like the IDE subsystem
does, and by clarifying the names of the ioctl commands.

Signed-off-by: Arnd Bergmann 
Reported-by: Soohoon Lee 
Tested-by: Soohoon Lee 
Cc: stable@vger.kernel.org
Signed-off-by: Tejun Heo 
Signed-off-by: Sasha Levin

nfs: fix nfs_size_to_loff_t

2016-03-08T02:12:58+00:00

[ Upstream commit 50ab8ec74a153eb30db26529088bc57dd700b24c ]

See http: //www.infradead.org/rpr.html
X-Evolution-Source: 1451162204.2173.11@leira.trondhjem.org
Content-Transfer-Encoding: 8bit
Mime-Version: 1.0

We support OFFSET_MAX just fine, so don't round down below it.  Also
switch to using min_t to make the helper more readable.

Signed-off-by: Christoph Hellwig 
Fixes: 433c92379d9c ("NFS: Clean up nfs_size_to_loff_t()")
Cc: stable@vger.kernel.org # 2.6.23+
Signed-off-by: Trond Myklebust 
Signed-off-by: Sasha Levin

tracing: Fix freak link error caused by branch tracer

2016-03-04T15:18:42+00:00

[ Upstream commit b33c8ff4431a343561e2319f17c14286f2aa52e2 ]

In my randconfig tests, I came across a bug that involves several
components:

* gcc-4.9 through at least 5.3
* CONFIG_GCOV_PROFILE_ALL enabling -fprofile-arcs for all files
* CONFIG_PROFILE_ALL_BRANCHES overriding every if()
* The optimized implementation of do_div() that tries to
  replace a library call with an division by multiplication
* code in drivers/media/dvb-frontends/zl10353.c doing

        u32 adc_clock = 450560; /* 45.056 MHz */
        if (state->config.adc_clock)
                adc_clock = state->config.adc_clock;
        do_div(value, adc_clock);

In this case, gcc fails to determine whether the divisor
in do_div() is __builtin_constant_p(). In particular, it
concludes that __builtin_constant_p(adc_clock) is false, while
__builtin_constant_p(!!adc_clock) is true.

That in turn throws off the logic in do_div() that also uses
__builtin_constant_p(), and instead of picking either the
constant- optimized division, and the code in ilog2() that uses
__builtin_constant_p() to figure out whether it knows the answer at
compile time. The result is a link error from failing to find
multiple symbols that should never have been called based on
the __builtin_constant_p():

dvb-frontends/zl10353.c:138: undefined reference to `____ilog2_NaN'
dvb-frontends/zl10353.c:138: undefined reference to `__aeabi_uldivmod'
ERROR: "____ilog2_NaN" [drivers/media/dvb-frontends/zl10353.ko] undefined!
ERROR: "__aeabi_uldivmod" [drivers/media/dvb-frontends/zl10353.ko] undefined!

This patch avoids the problem by changing __trace_if() to check
whether the condition is known at compile-time to be nonzero, rather
than checking whether it is actually a constant.

I see this one link error in roughly one out of 1600 randconfig builds
on ARM, and the patch fixes all known instances.

Link: http://lkml.kernel.org/r/1455312410-1058841-1-git-send-email-arnd@arndb.de

Acked-by: Nicolas Pitre 
Fixes: ab3c9c686e22 ("branch tracer, intel-iommu: fix build with CONFIG_BRANCH_TRACER=y")
Cc: stable@vger.kernel.org # v2.6.30+
Signed-off-by: Arnd Bergmann 
Signed-off-by: Steven Rostedt 
Signed-off-by: Sasha Levin

tracepoints: Do not trace when cpu is offline

2016-03-04T15:18:42+00:00

[ Upstream commit f37755490fe9bf76f6ba1d8c6591745d3574a6a6 ]

The tracepoint infrastructure uses RCU sched protection to enable and
disable tracepoints safely. There are some instances where tracepoints are
used in infrastructure code (like kfree()) that get called after a CPU is
going offline, and perhaps when it is coming back online but hasn't been
registered yet.

This can probuce the following warning:

 [ INFO: suspicious RCU usage. ]
 4.4.0-00006-g0fe53e8-dirty #34 Tainted: G S
 -------------------------------
 include/trace/events/kmem.h:141 suspicious rcu_dereference_check() usage!

 other info that might help us debug this:

 RCU used illegally from offline CPU!  rcu_scheduler_active = 1, debug_locks = 1
 no locks held by swapper/8/0.

 stack backtrace:
  CPU: 8 PID: 0 Comm: swapper/8 Tainted: G S              4.4.0-00006-g0fe53e8-dirty #34
  Call Trace:
  [c0000005b76c78d0] [c0000000008b9540] .dump_stack+0x98/0xd4 (unreliable)
  [c0000005b76c7950] [c00000000010c898] .lockdep_rcu_suspicious+0x108/0x170
  [c0000005b76c79e0] [c00000000029adc0] .kfree+0x390/0x440
  [c0000005b76c7a80] [c000000000055f74] .destroy_context+0x44/0x100
  [c0000005b76c7b00] [c0000000000934a0] .__mmdrop+0x60/0x150
  [c0000005b76c7b90] [c0000000000e3ff0] .idle_task_exit+0x130/0x140
  [c0000005b76c7c20] [c000000000075804] .pseries_mach_cpu_die+0x64/0x310
  [c0000005b76c7cd0] [c000000000043e7c] .cpu_die+0x3c/0x60
  [c0000005b76c7d40] [c0000000000188d8] .arch_cpu_idle_dead+0x28/0x40
  [c0000005b76c7db0] [c000000000101e6c] .cpu_startup_entry+0x50c/0x560
  [c0000005b76c7ed0] [c000000000043bd8] .start_secondary+0x328/0x360
  [c0000005b76c7f90] [c000000000008a6c] start_secondary_prolog+0x10/0x14

This warning is not a false positive either. RCU is not protecting code that
is being executed while the CPU is offline.

Instead of playing "whack-a-mole(TM)" and adding conditional statements to
the tracepoints we find that are used in this instance, simply add a
cpu_online() test to the tracepoint code where the tracepoint will be
ignored if the CPU is offline.

Use of raw_smp_processor_id() is fine, as there should never be a case where
the tracepoint code goes from running on a CPU that is online and suddenly
gets migrated to a CPU that is offline.

Link: http://lkml.kernel.org/r/1455387773-4245-1-git-send-email-kda@linux-powerpc.org

Reported-by: Denis Kirjanov 
Fixes: 97e1c18e8d17b ("tracing: Kernel Tracepoints")
Cc: stable@vger.kernel.org # v2.6.28+
Signed-off-by: Steven Rostedt 
Signed-off-by: Sasha Levin

pty: make sure super_block is still valid in final /dev/tty close

2016-03-02T20:19:16+00:00

[ Upstream commit 1f55c718c290616889c04946864a13ef30f64929 ]

Considering current pty code and multiple devpts instances, it's possible
to umount a devpts file system while a program still has /dev/tty opened
pointing to a previosuly closed pty pair in that instance. In the case all
ptmx and pts/N files are closed, umount can be done. If the program closes
/dev/tty after umount is done, devpts_kill_index will use now an invalid
super_block, which was already destroyed in the umount operation after
running ->kill_sb. This is another "use after free" type of issue, but now
related to the allocated super_block instance.

To avoid the problem (warning at ida_remove and potential crashes) for
this specific case, I added two functions in devpts which grabs additional
references to the super_block, which pty code now uses so it makes sure
the super block structure is still valid until pty shutdown is done.
I also moved the additional inode references to the same functions, which
also covered similar case with inode being freed before /dev/tty final
close/shutdown.

Signed-off-by: Herton R. Krzesinski 
Cc: stable@vger.kernel.org # 2.6.29+
Reviewed-by: Peter Hurley 
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

net: filter: make JITs zero A for SKF_AD_ALU_XOR_X

2016-02-15T20:42:43+00:00

[ Upstream commit 55795ef5469290f89f04e12e662ded604909e462 ]

The SKF_AD_ALU_XOR_X ancillary is not like the other ancillary data
instructions since it XORs A with X while all the others replace A with
some loaded value.  All the BPF JITs fail to clear A if this is used as
the first instruction in a filter.  This was found using american fuzzy
lop.

Add a helper to determine if A needs to be cleared given the first
instruction in a filter, and use this in the JITs.  Except for ARM, the
rest have only been compile-tested.

Fixes: 3480593131e0 ("net: filter: get rid of BPF_S_* enum")
Signed-off-by: Rabin Vincent 
Acked-by: Daniel Borkmann 
Acked-by: Alexei Starovoitov 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin

unix: properly account for FDs passed over unix sockets

2016-02-15T20:42:43+00:00

[ Upstream commit 712f4aad406bb1ed67f3f98d04c044191f0ff593 ]

It is possible for a process to allocate and accumulate far more FDs than
the process' limit by sending them over a unix socket then closing them
to keep the process' fd count low.

This change addresses this problem by keeping track of the number of FDs
in flight per user and preventing non-privileged processes from having
more FDs in flight than their configured FD limit.

Reported-by: socketpair@gmail.com
Reported-by: Tetsuo Handa 
Mitigates: CVE-2013-4312 (Linux 2.0+)
Suggested-by: Linus Torvalds 
Acked-by: Hannes Frederic Sowa 
Signed-off-by: Willy Tarreau 
Signed-off-by: David S. Miller 
Signed-off-by: Sasha Levin