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  13. Mar 05, 2015
    • Steven Rostedt (Red Hat)'s avatar
      seq_buf: Fix seq_buf_bprintf() truncation · 4d4eb4d4
      Steven Rostedt (Red Hat) authored 
      In seq_buf_bprintf(), bstr_printf() is used to copy the format into the
buffer remaining in the seq_buf structure. The return of bstr_printf()
is the amount of characters written to the buffer excluding the '\0',
unless the line was truncated!

If the line copied does not fit, it is truncated, and a '\0' is added
to the end of the buffer. But in this case, '\0' is included in the length
of the line written. To know if the buffer had overflowed, the return
length will be the same or greater than the length of the buffer passed in.

The check in seq_buf_bprintf() only checked if the length returned from
bstr_printf() would fit in the buffer, as the seq_buf_bprintf() is only
to be an all or nothing command. It either writes all the string into
the seq_buf, or none of it. If the string is truncated, the pointers
inside the seq_buf must be reset to what they were when the function was
called. This is not the case. On overflow, it copies only part of the string.

The fix is to change the overflow check to see if the length returned from
bstr_printf() is less than the length remaining in the seq_buf buffer, and not
if it is less than or equal to as it currently does. Then seq_buf_bprintf()
will know if the write from bstr_printf() was truncated or not.

Link: http://lkml.kernel.org/r/1425500481.2712.27.camel@perches.com



Cc: stable@vger.kernel.org
Reported-by: default avatarJoe Perches <joe@perches.com>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      4d4eb4d4
  15. Mar 04, 2015
    • Steven Rostedt (Red Hat)'s avatar
      seq_buf: Fix seq_buf_vprintf() truncation · 4a8fe4e1
      Steven Rostedt (Red Hat) authored 
      

In seq_buf_vprintf(), vsnprintf() is used to copy the format into the
buffer remaining in the seq_buf structure. The return of vsnprintf()
is the amount of characters written to the buffer excluding the '\0',
unless the line was truncated!

If the line copied does not fit, it is truncated, and a '\0' is added
to the end of the buffer. But in this case, '\0' is included in the length
of the line written. To know if the buffer had overflowed, the return
length will be the same as the length of the buffer passed in.

The check in seq_buf_vprintf() only checked if the length returned from
vsnprintf() would fit in the buffer, as the seq_buf_vprintf() is only
to be an all or nothing command. It either writes all the string into
the seq_buf, or none of it. If the string is truncated, the pointers
inside the seq_buf must be reset to what they were when the function was
called. This is not the case. On overflow, it copies only part of the string.

The fix is to change the overflow check to see if the length returned from
vsnprintf() is less than the length remaining in the seq_buf buffer, and not
if it is less than or equal to as it currently does. Then seq_buf_vprintf()
will know if the write from vsnpritnf() was truncated or not.

Cc: stable@vger.kernel.org
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
      4a8fe4e1
  17. Feb 27, 2015
    • Eric Dumazet's avatar
      rhashtable: use cond_resched() · 5beb5c90
      Eric Dumazet authored 
      

If a hash table has 128 slots and 16384 elems, expand to 256 slots
takes more than one second. For larger sets, a soft lockup is detected.

Holding cpu for that long, even in a work queue is a show stopper
for non preemptable kernels.

cond_resched() at strategic points to allow process scheduler
to reschedule us.

Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Acked-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      5beb5c90
    • Daniel Borkmann's avatar
      rhashtable: remove indirection for grow/shrink decision functions · 4c4b52d9
      Daniel Borkmann authored 
      Currently, all real users of rhashtable default their grow and shrink
decision functions to rht_grow_above_75() and rht_shrink_below_30(),
so that there's currently no need to have this explicitly selectable.

It can/should be generic and private inside rhashtable until a real
use case pops up. Since we can make this private, we'll save us this
additional indirection layer and can improve insertion/deletion time
as well.

Reference: http://patchwork.ozlabs.org/patch/443040/


Suggested-by: default avatarDavid S. Miller <davem@davemloft.net>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarThomas Graf <tgraf@suug.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      4c4b52d9
    • Daniel Borkmann's avatar
      rhashtable: unconditionally grow when max_shift is not specified · 8331de75
      Daniel Borkmann authored 
      

While commit c0c09bfd ("rhashtable: avoid unnecessary wakeup for
worker queue") rightfully moved part of the decision making of
whether we should expand or shrink from the expand/shrink functions
themselves into insert/delete functions in order to avoid unnecessary
worker wake-ups, it however introduced a regression by doing so.

Before that change, if no max_shift was specified (= 0) on rhashtable
initialization, rhashtable_expand() would just grow unconditionally
and lets the available memory be the limiting factor. After that
change, if no max_shift was specified, there would be _no_ expansion
step at all.

Given that netlink and tipc have a max_shift specified, it was not
visible there, but Josh Hunt reported that if nft that starts out
with a default element hint of 3 if not otherwise provided, would
slow i.e. inserts down trememdously as it cannot grow larger to
relax table occupancy.

Given that the test case verifies shrinks/expands manually, we also
must remove pointer to the helper functions to explicitly avoid
parallel resizing on insertions/deletions. test_bucket_stats() and
test_rht_lookup() could also be wrapped around rhashtable mutex to
explicitly synchronize a walk from resizing, but I think that defeats
the actual test case which intended to have explicit test steps,
i.e. 1) inserts, 2) expands, 3) shrinks, 4) deletions, with object
verification after each stage.

Reported-by: default avatarJosh Hunt <johunt@akamai.com>
Fixes: c0c09bfd ("rhashtable: avoid unnecessary wakeup for worker queue")
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Cc: Ying Xue <ying.xue@windriver.com>
Cc: Josh Hunt <johunt@akamai.com>
Acked-by: default avatarThomas Graf <tgraf@suug.ch>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
      8331de75
  19. Feb 23, 2015
  21. Feb 20, 2015
  23. Feb 17, 2015
  25. Feb 14, 2015
    • Andrey Ryabinin's avatar
      kasan: enable instrumentation of global variables · bebf56a1
      Andrey Ryabinin authored 
      

This feature let us to detect accesses out of bounds of global variables.
This will work as for globals in kernel image, so for globals in modules.
Currently this won't work for symbols in user-specified sections (e.g.
__init, __read_mostly, ...)

The idea of this is simple.  Compiler increases each global variable by
redzone size and add constructors invoking __asan_register_globals()
function.  Information about global variable (address, size, size with
redzone ...) passed to __asan_register_globals() so we could poison
variable's redzone.

This patch also forces module_alloc() to return 8*PAGE_SIZE aligned
address making shadow memory handling (
kasan_module_alloc()/kasan_module_free() ) more simple.  Such alignment
guarantees that each shadow page backing modules address space correspond
to only one module_alloc() allocation.

Signed-off-by: default avatarAndrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: default avatarAndrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      bebf56a1
    • Andrey Ryabinin's avatar
      lib: add kasan test module · 3f15801c
      Andrey Ryabinin authored 
      

This is a test module doing various nasty things like out of bounds
accesses, use after free.  It is useful for testing kernel debugging
features like kernel address sanitizer.

It mostly concentrates on testing of slab allocator, but we might want to
add more different stuff here in future (like stack/global variables out
of bounds accesses and so on).

Signed-off-by: default avatarAndrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: default avatarAndrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      3f15801c
    • Andrey Ryabinin's avatar
      mm: slub: add kernel address sanitizer support for slub allocator · 0316bec2
      Andrey Ryabinin authored 
      

With this patch kasan will be able to catch bugs in memory allocated by
slub.  Initially all objects in newly allocated slab page, marked as
redzone.  Later, when allocation of slub object happens, requested by
caller number of bytes marked as accessible, and the rest of the object
(including slub's metadata) marked as redzone (inaccessible).

We also mark object as accessible if ksize was called for this object.
There is some places in kernel where ksize function is called to inquire
size of really allocated area.  Such callers could validly access whole
allocated memory, so it should be marked as accessible.

Code in slub.c and slab_common.c files could validly access to object's
metadata, so instrumentation for this files are disabled.

Signed-off-by: default avatarAndrey Ryabinin <a.ryabinin@samsung.com>
Signed-off-by: default avatarDmitry Chernenkov <dmitryc@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Signed-off-by: default avatarAndrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      0316bec2
    • Andrey Ryabinin's avatar
      x86_64: add KASan support · ef7f0d6a
      Andrey Ryabinin authored 
      

This patch adds arch specific code for kernel address sanitizer.

16TB of virtual addressed used for shadow memory.  It's located in range
[ffffec0000000000 - fffffc0000000000] between vmemmap and %esp fixup
stacks.

At early stage we map whole shadow region with zero page.  Latter, after
pages mapped to direct mapping address range we unmap zero pages from
corresponding shadow (see kasan_map_shadow()) and allocate and map a real
shadow memory reusing vmemmap_populate() function.

Also replace __pa with __pa_nodebug before shadow initialized.  __pa with
CONFIG_DEBUG_VIRTUAL=y make external function call (__phys_addr)
__phys_addr is instrumented, so __asan_load could be called before shadow
area initialized.

Signed-off-by: default avatarAndrey Ryabinin <a.ryabinin@samsung.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Konstantin Serebryany <kcc@google.com>
Cc: Dmitry Chernenkov <dmitryc@google.com>
Signed-off-by: default avatarAndrey Konovalov <adech.fo@gmail.com>
Cc: Yuri Gribov <tetra2005@gmail.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Jim Davis <jim.epost@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      ef7f0d6a