linux-stable.git/arch/mips, branch v3.16.45

mm: larger stack guard gap, between vmas

2017-07-02T16:13:02+00:00

commit 1be7107fbe18eed3e319a6c3e83c78254b693acb upstream.

Stack guard page is a useful feature to reduce a risk of stack smashing
into a different mapping. We have been using a single page gap which
is sufficient to prevent having stack adjacent to a different mapping.
But this seems to be insufficient in the light of the stack usage in
userspace. E.g. glibc uses as large as 64kB alloca() in many commonly
used functions. Others use constructs liks gid_t buffer[NGROUPS_MAX]
which is 256kB or stack strings with MAX_ARG_STRLEN.

This will become especially dangerous for suid binaries and the default
no limit for the stack size limit because those applications can be
tricked to consume a large portion of the stack and a single glibc call
could jump over the guard page. These attacks are not theoretical,
unfortunatelly.

Make those attacks less probable by increasing the stack guard gap
to 1MB (on systems with 4k pages; but make it depend on the page size
because systems with larger base pages might cap stack allocations in
the PAGE_SIZE units) which should cover larger alloca() and VLA stack
allocations. It is obviously not a full fix because the problem is
somehow inherent, but it should reduce attack space a lot.

One could argue that the gap size should be configurable from userspace,
but that can be done later when somebody finds that the new 1MB is wrong
for some special case applications.  For now, add a kernel command line
option (stack_guard_gap) to specify the stack gap size (in page units).

Implementation wise, first delete all the old code for stack guard page:
because although we could get away with accounting one extra page in a
stack vma, accounting a larger gap can break userspace - case in point,
a program run with "ulimit -S -v 20000" failed when the 1MB gap was
counted for RLIMIT_AS; similar problems could come with RLIMIT_MLOCK
and strict non-overcommit mode.

Instead of keeping gap inside the stack vma, maintain the stack guard
gap as a gap between vmas: using vm_start_gap() in place of vm_start
(or vm_end_gap() in place of vm_end if VM_GROWSUP) in just those few
places which need to respect the gap - mainly arch_get_unmapped_area(),
and and the vma tree's subtree_gap support for that.

Original-patch-by: Oleg Nesterov 
Original-patch-by: Michal Hocko 
Signed-off-by: Hugh Dickins 
Acked-by: Michal Hocko 
Tested-by: Helge Deller  # parisc
Signed-off-by: Linus Torvalds 
[Hugh Dickins: Backported to 3.16]
Signed-off-by: Ben Hutchings

MIPS: BCM47XX: Fix button inversion for Asus WL-500W

2017-06-05T20:17:10+00:00

commit bdfdaf1a016ef09cb941f2edad485a713510b8d5 upstream.

The Asus WL-500W buttons are active high, but the software treats them
as active low. Fix the inverted logic.

Fixes: 3be972556fa1 ("MIPS: BCM47XX: Import buttons database from OpenWrt")
Signed-off-by: Mirko Parthey 
Acked-by: Rafał Miłecki 
Cc: Hauke Mehrtens 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/15295/
Signed-off-by: James Hogan 
Signed-off-by: Ben Hutchings

MIPS: ip27: Disable qlge driver in defconfig

2017-06-05T20:17:10+00:00

commit b617649468390713db1515ea79fc772d2eb897a8 upstream.

One of the last remaining failures in kernelci.org is for a gcc bug:

drivers/net/ethernet/qlogic/qlge/qlge_main.c:4819:1: error: insn does not satisfy its constraints:
drivers/net/ethernet/qlogic/qlge/qlge_main.c:4819:1: internal compiler error: in extract_constrain_insn, at recog.c:2190

This is apparently broken in gcc-6 but fixed in gcc-7, and I cannot
reproduce the problem here. However, it is clear that ip27_defconfig
does not actually need this driver as the platform has only PCI-X but
not PCIe, and the qlge adapter in turn is PCIe-only.

The driver was originally enabled in 2010 along with lots of other
drivers.

Fixes: 59d302b342e5 ("MIPS: IP27: Make defconfig useful again.")
Signed-off-by: Arnd Bergmann 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15197/
Signed-off-by: James Hogan 
Signed-off-by: Ben Hutchings

MIPS: OCTEON: Fix copy_from_user fault handling for large buffers

2017-06-05T20:17:10+00:00

commit 884b426917e4b3c85f33b382c792a94305dfdd62 upstream.

If copy_from_user is called with a large buffer (>= 128 bytes) and the
userspace buffer refers partially to unreadable memory, then it is
possible for Octeon's copy_from_user to report the wrong number of bytes
have been copied. In the case where the buffer size is an exact multiple
of 128 and the fault occurs in the last 64 bytes, copy_from_user will
report that all the bytes were copied successfully but leave some
garbage in the destination buffer.

The bug is in the main __copy_user_common loop in octeon-memcpy.S where
in the middle of the loop, src and dst are incremented by 128 bytes. The
l_exc_copy fault handler is used after this but that assumes that
"src < THREAD_BUADDR($28)". This is not the case if src has already been
incremented.

Fix by adding an extra fault handler which rewinds the src and dst
pointers 128 bytes before falling though to l_exc_copy.

Thanks to the pwritev test from the strace test suite for originally
highlighting this bug!

Fixes: 5b3b16880f40 ("MIPS: Add Cavium OCTEON processor support ...")
Signed-off-by: James Cowgill 
Acked-by: David Daney 
Reviewed-by: James Hogan 
Cc: Ralf Baechle 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14978/
Signed-off-by: James Hogan 
Signed-off-by: Ben Hutchings

MIPS: Fix special case in 64 bit IP checksumming.

2017-06-05T20:17:10+00:00

commit 66fd848cadaa6be974a8c780fbeb328f0af4d3bd upstream.

For certain arguments such as saddr = 0xc0a8fd60, daddr = 0xc0a8fda1,
len = 80, proto = 17, sum = 0x7eae049d there will be a carry when
folding the intermediate 64 bit checksum to 32 bit but the code doesn't
add the carry back to the one's complement sum, thus an incorrect result
will be generated.

Reported-by: Mark Zhang 
Signed-off-by: Ralf Baechle 
Reviewed-by: James Hogan 
Signed-off-by: James Hogan 
Signed-off-by: Ben Hutchings

MIPS: 'make -s' should be silent

2017-06-05T20:16:58+00:00

commit 8c9b23ffb3f92ffa4cbe37b1bab4542586e0bfd1 upstream.

A clean mips64 build produces no output except for two lines:

  Checking missing-syscalls for N32
  Checking missing-syscalls for O32

On other architectures, there is no output at all, so let's do the
same here for the sake of build testing. The 'kecho' macro is used
to print the message on a normal build but skip it with 'make -s'.

Fixes: e48ce6b8df5b ("[MIPS] Simplify missing-syscalls for N32 and O32")
Signed-off-by: Arnd Bergmann 
Cc: Paul Burton 
Cc: Matt Redfearn 
Cc: Huacai Chen 
Cc: Maarten ter Huurne 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/15040/
Signed-off-by: Ralf Baechle 
Signed-off-by: Ben Hutchings

MIPS: Netlogic: Fix assembler warning from smpboot.S

2017-06-05T20:16:46+00:00

commit a8b3b0c94ac282628f0668d1366239a3fa72dc9d upstream.

The netlogic platform can be built for either MIPS32 or MIPS64, and when
built for MIPS32 (as by nlm_xlr_defconfig) the use of the dla
pseudo-instruction leads to warnings such as the following from recent
versions of the GNU assembler:

  arch/mips/netlogic/common/smpboot.S: Assembler messages:
  arch/mips/netlogic/common/smpboot.S:62: Warning: dla used to load 32-bit register; recommend using la instead
  arch/mips/netlogic/common/smpboot.S:63: Warning: dla used to load 32-bit register; recommend using la instead

Avoid these warnings by using the PTR_LA macro to make use of the
appropriate la or dla pseudo-instruction for the build.

Signed-off-by: Paul Burton 
Fixes: 66d29985fab8 ("MIPS: Netlogic: Merge some of XLR/XLP wakup code")
Cc: James Hogan 
Cc: Jayachandran C 
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14185/
Signed-off-by: Ralf Baechle 
Signed-off-by: Ben Hutchings

MIPS: Handle microMIPS jumps in the same way as MIPS32/MIPS64 jumps

2017-06-05T20:16:46+00:00

commit 096a0de427ea333f56f0ee00328cff2a2731bcf1 upstream.

is_jump_ins() checks for plain jump ("j") instructions since commit
e7438c4b893e ("MIPS: Fix sibling call handling in get_frame_info") but
that commit didn't make the same change to the microMIPS code, leaving
it inconsistent with the MIPS32/MIPS64 code. Handle the microMIPS
encoding of the jump instruction too such that it behaves consistently.

Signed-off-by: Paul Burton 
Fixes: e7438c4b893e ("MIPS: Fix sibling call handling in get_frame_info")
Cc: Tony Wu 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14533/
Signed-off-by: Ralf Baechle 
Signed-off-by: Ben Hutchings

MIPS: Calculate microMIPS ra properly when unwinding the stack

2017-06-05T20:16:46+00:00

commit bb9bc4689b9c635714fbcd5d335bad9934a7ebfc upstream.

get_frame_info() calculates the offset of the return address within a
stack frame simply by dividing a the bottom 16 bits of the instruction,
treated as a signed integer, by the size of a long. Whilst this works
for MIPS32 & MIPS64 ISAs where the sw or sd instructions are used, it's
incorrect for microMIPS where encodings differ. The result is that we
typically completely fail to unwind the stack on microMIPS.

Fix this by adjusting is_ra_save_ins() to calculate the return address
offset, and take into account the various different encodings there in
the same place as we consider whether an instruction is storing the
ra/$31 register.

With this we are now able to unwind the stack for kernels targetting the
microMIPS ISA, for example we can produce:

    Call Trace:
    [<80109e1f>] show_stack+0x63/0x7c
    [<8011ea17>] __warn+0x9b/0xac
    [<8011ea45>] warn_slowpath_fmt+0x1d/0x20
    [<8013fe53>] register_console+0x43/0x314
    [<8067c58d>] of_setup_earlycon+0x1dd/0x1ec
    [<8067f63f>] early_init_dt_scan_chosen_stdout+0xe7/0xf8
    [<8066c115>] do_early_param+0x75/0xac
    [<801302f9>] parse_args+0x1dd/0x308
    [<8066c459>] parse_early_options+0x25/0x28
    [<8066c48b>] parse_early_param+0x2f/0x38
    [<8066e8cf>] setup_arch+0x113/0x488
    [<8066c4f3>] start_kernel+0x57/0x328
    ---[ end trace 0000000000000000 ]---

Whereas previously we only produced:

    Call Trace:
    [<80109e1f>] show_stack+0x63/0x7c
    ---[ end trace 0000000000000000 ]---

Signed-off-by: Paul Burton 
Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.")
Cc: Leonid Yegoshin 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14532/
Signed-off-by: Ralf Baechle 
Signed-off-by: Ben Hutchings

MIPS: Fix is_jump_ins() handling of 16b microMIPS instructions

2017-06-05T20:16:45+00:00

commit 67c75057709a6d85c681c78b9b2f9b71191f01a2 upstream.

is_jump_ins() checks 16b instruction fields without verifying that the
instruction is indeed 16b, as is done by is_ra_save_ins() &
is_sp_move_ins(). Add the appropriate check.

Signed-off-by: Paul Burton 
Fixes: 34c2f668d0f6 ("MIPS: microMIPS: Add unaligned access support.")
Cc: Leonid Yegoshin 
Cc: linux-mips@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/14531/
Signed-off-by: Ralf Baechle 
Signed-off-by: Ben Hutchings