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  1. 03 Jul, 2018 36 commits
  3. 26 Jun, 2018 4 commits
    • Greg Kroah-Hartman's avatar
      Linux 4.14.52 · a26899e0
      Greg Kroah-Hartman authored
      a26899e0
    • Vlastimil Babka's avatar
      mm, page_alloc: do not break __GFP_THISNODE by zonelist reset · 1d26c112
      Vlastimil Babka authored 
      commit 7810e678 upstream.

In __alloc_pages_slowpath() we reset zonelist and preferred_zoneref for
allocations that can ignore memory policies.  The zonelist is obtained
from current CPU's node.  This is a problem for __GFP_THISNODE
allocations that want to allocate on a different node, e.g.  because the
allocating thread has been migrated to a different CPU.

This has been observed to break SLAB in our 4.4-based kernel, because
there it relies on __GFP_THISNODE working as intended.  If a slab page
is put on wrong node's list, then further list manipulations may corrupt
the list because page_to_nid() is used to determine which node's
list_lock should be locked and thus we may take a wrong lock and race.

Current SLAB implementation seems to be immune by luck thanks to commit
511e3a05 ("mm/slab: make cache_grow() handle the page allocated on
arbitrary node") but there may be others assuming that __GFP_THISNODE
works as promised.

We can fix it by simply removing the zonelist reset completely.  There
is actually no reason to reset it, because memory policies and cpusets
don't affect the zonelist choice in the first place.  This was different
when commit 183f6371 ("mm: ignore mempolicies when using
ALLOC_NO_WATERMARK") introduced the code, as mempolicies provided their
own restricted zonelists.

We might consider this for 4.17 although I don't know if there's
anything currently broken.

SLAB is currently not affected, but in kernels older than 4.7 that don't
yet have 511e3a05 ("mm/slab: make cache_grow() handle the page
allocated on arbitrary node") it is.  That's at least 4.4 LTS.  Older
ones I'll have to check.

So stable backports should be more important, but will have to be
reviewed carefully, as the code went through many changes.  BTW I think
that also the ac->preferred_zoneref reset is currently useless if we
don't also reset ac->nodemask from a mempolicy to NULL first (which we
probably should for the OOM victims etc?), but I would leave that for a
separate patch.

Link: http://lkml.kernel.org/r/20180525130853.13915-1-vbabka@suse.czSigned-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Fixes: 183f6371 ("mm: ignore mempolicies when using ALLOC_NO_WATERMARK")
Acked-by: default avatarMel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      1d26c112
    • Thadeu Lima de Souza Cascardo's avatar
      fs/binfmt_misc.c: do not allow offset overflow · 250edf95
      Thadeu Lima de Souza Cascardo authored 
      commit 5cc41e09 upstream.

WHen registering a new binfmt_misc handler, it is possible to overflow
the offset to get a negative value, which might crash the system, or
possibly leak kernel data.

Here is a crash log when 2500000000 was used as an offset:

  BUG: unable to handle kernel paging request at ffff989cfd6edca0
  IP: load_misc_binary+0x22b/0x470 [binfmt_misc]
  PGD 1ef3e067 P4D 1ef3e067 PUD 0
  Oops: 0000 [#1] SMP NOPTI
  Modules linked in: binfmt_misc kvm_intel ppdev kvm irqbypass joydev input_leds serio_raw mac_hid parport_pc qemu_fw_cfg parpy
  CPU: 0 PID: 2499 Comm: bash Not tainted 4.15.0-22-generic #24-Ubuntu
  Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.11.1-1 04/01/2014
  RIP: 0010:load_misc_binary+0x22b/0x470 [binfmt_misc]
  Call Trace:
    search_binary_handler+0x97/0x1d0
    do_execveat_common.isra.34+0x667/0x810
    SyS_execve+0x31/0x40
    do_syscall_64+0x73/0x130
    entry_SYSCALL_64_after_hwframe+0x3d/0xa2

Use kstrtoint instead of simple_strtoul.  It will work as the code
already set the delimiter byte to '\0' and we only do it when the field
is not empty.

Tested with offsets -1, 2500000000, UINT_MAX and INT_MAX.  Also tested
with examples documented at Documentation/admin-guide/binfmt-misc.rst
and other registrations from packages on Ubuntu.

Link: http://lkml.kernel.org/r/20180529135648.14254-1-cascardo@canonical.com
Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Signed-off-by: default avatarThadeu Lima de Souza Cascardo <cascardo@canonical.com>
Reviewed-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: <stable@vger.kernel.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      250edf95
    • Michael S. Tsirkin's avatar
      vhost: fix info leak due to uninitialized memory · 7446344b
      Michael S. Tsirkin authored 
      commit 670ae9ca upstream.

struct vhost_msg within struct vhost_msg_node is copied to userspace.
Unfortunately it turns out on 64 bit systems vhost_msg has padding after
type which gcc doesn't initialize, leaking 4 uninitialized bytes to
userspace.

This padding also unfortunately means 32 bit users of this interface are
broken on a 64 bit kernel which will need to be fixed separately.

Fixes: CVE-2018-1118
Cc: stable@vger.kernel.org
Reported-by: default avatarKevin Easton <kevin@guarana.org>
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Reported-by: syzbot+87cfa083e727a224754b@syzkaller.appspotmail.com
Signed-off-by: default avatarMichael S. Tsirkin <mst@redhat.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      7446344b
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