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Sean Christopherson c87661f855 KVM: Free new dirty bitmap if creating a new memslot fails 
Fix a goof in kvm_prepare_memory_region() where KVM fails to free the
new memslot's dirty bitmap during a CREATE action if
kvm_arch_prepare_memory_region() fails.  The logic is supposed to detect
if the bitmap was allocated and thus needs to be freed, versus if the
bitmap was inherited from the old memslot and thus needs to be kept.  If
there is no old memslot, then obviously the bitmap can't have been
inherited

The bug was exposed by commit 86931ff720 ("KVM: x86/mmu: Do not create
SPTEs for GFNs that exceed host.MAXPHYADDR"), which made it trivally easy
for syzkaller to trigger failure during kvm_arch_prepare_memory_region(),
but the bug can be hit other ways too, e.g. due to -ENOMEM when
allocating x86's memslot metadata.

The backtrace from kmemleak:

  __vmalloc_node_range+0xb40/0xbd0 mm/vmalloc.c:3195
  __vmalloc_node mm/vmalloc.c:3232 [inline]
  __vmalloc+0x49/0x50 mm/vmalloc.c:3246
  __vmalloc_array mm/util.c:671 [inline]
  __vcalloc+0x49/0x70 mm/util.c:694
  kvm_alloc_dirty_bitmap virt/kvm/kvm_main.c:1319
  kvm_prepare_memory_region virt/kvm/kvm_main.c:1551
  kvm_set_memslot+0x1bd/0x690 virt/kvm/kvm_main.c:1782
  __kvm_set_memory_region+0x689/0x750 virt/kvm/kvm_main.c:1949
  kvm_set_memory_region virt/kvm/kvm_main.c:1962
  kvm_vm_ioctl_set_memory_region virt/kvm/kvm_main.c:1974
  kvm_vm_ioctl+0x377/0x13a0 virt/kvm/kvm_main.c:4528
  vfs_ioctl fs/ioctl.c:51
  __do_sys_ioctl fs/ioctl.c:870
  __se_sys_ioctl fs/ioctl.c:856
  __x64_sys_ioctl+0xfc/0x140 fs/ioctl.c:856
  do_syscall_x64 arch/x86/entry/common.c:50
  do_syscall_64+0x35/0xb0 arch/x86/entry/common.c:80
  entry_SYSCALL_64_after_hwframe+0x44/0xae

And the relevant sequence of KVM events:

  ioctl(3, KVM_CREATE_VM, 0)              = 4
  ioctl(4, KVM_SET_USER_MEMORY_REGION, {slot=0,
                                        flags=KVM_MEM_LOG_DIRTY_PAGES,
                                        guest_phys_addr=0x10000000000000,
                                        memory_size=4096,
                                        userspace_addr=0x20fe8000}
       ) = -1 EINVAL (Invalid argument)

Fixes: 244893fa28 ("KVM: Dynamically allocate "new" memslots from the get-go")
Cc: stable@vger.kernel.org
Reported-by: syzbot+8606b8a9cc97a63f1c87@syzkaller.appspotmail.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-Id: <20220518003842.1341782-1-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2022-05-20 13:02:05 -04:00
arch kvm: x86/pmu: Fix the compare function used by the pmu event filter 2022-05-20 07:06:29 -04:00
block block: don't print I/O error warning for dead disks 2022-04-15 06:33:03 -06:00
certs Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
crypto for-5.18/64bit-pi-2022-03-25 2022-03-26 12:01:35 -07:00
Documentation Merge branch 'kvm-fixes-for-5.18-rc5' into HEAD 2022-04-29 12:39:34 -04:00
drivers xen: branch for v5.18-rc3 2022-04-17 10:29:10 -07:00
fs Merge branch 'akpm' (patches from Andrew) 2022-04-15 15:57:18 -07:00
include Merge branch 'kvm-fixes-for-5.18-rc5' into HEAD 2022-04-29 12:39:34 -04:00
init Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
ipc fs: allocate inode by using alloc_inode_sb() 2022-03-22 15:57:03 -07:00
kernel A small set of fixes for the timers core: 2022-04-17 09:53:01 -07:00
lib Driver core changes for 5.18-rc2 2022-04-10 09:55:09 -10:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: kmemleak: take a full lowmem check in kmemleak_*_phys() 2022-04-15 14:49:56 -07:00
net Networking fixes for 5.18-rc3, including fixes from wireless and 2022-04-14 11:58:19 -07:00
samples dma-mapping updates for Linux 5.18 2022-03-29 08:50:14 -07:00
scripts hardening fixes for v5.18-rc3 2022-04-12 14:29:40 -10:00
security hardening updates for v5.18-rc1-fix1 2022-03-31 11:43:01 -07:00
sound sound fixes for 5.18-rc3 2022-04-14 11:08:12 -07:00
tools selftests: kvm/x86: Verify the pmu event filter matches the correct event 2022-05-20 07:06:55 -04:00
usr Kbuild updates for v5.18 2022-03-31 11:59:03 -07:00
virt KVM: Free new dirty bitmap if creating a new memslot fails 2022-05-20 13:02:05 -04:00
.clang-format genirq/msi: Make interrupt allocation less convoluted 2021-12-16 22:22:20 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore .gitignore: ignore only top-level modules.builtin 2021-05-02 00:43:35 +09:00
.mailmap mailmap: update Vasily Averin's email address 2022-04-08 14:20:36 -10:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: replace a Microchip AT91 maintainer 2022-02-09 11:30:01 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS ARM: SoC fixes for 5.18, part 2 2022-04-16 16:51:39 -07:00
Makefile Linux 5.18-rc3 2022-04-17 13:57:31 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.