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Stefan Hajnoczi f6f300ecc1 vfio/type1: fix cap_migration information leak 
[ Upstream commit cd24e2a60a ]

Fix an information leak where an uninitialized hole in struct
vfio_iommu_type1_info_cap_migration on the stack is exposed to userspace.

The definition of struct vfio_iommu_type1_info_cap_migration contains a hole as
shown in this pahole(1) output:

  struct vfio_iommu_type1_info_cap_migration {
          struct vfio_info_cap_header header;              /*     0     8 */
          __u32                      flags;                /*     8     4 */

          /* XXX 4 bytes hole, try to pack */

          __u64                      pgsize_bitmap;        /*    16     8 */
          __u64                      max_dirty_bitmap_size; /*    24     8 */

          /* size: 32, cachelines: 1, members: 4 */
          /* sum members: 28, holes: 1, sum holes: 4 */
          /* last cacheline: 32 bytes */
  };

The cap_mig variable is filled in without initializing the hole:

  static int vfio_iommu_migration_build_caps(struct vfio_iommu *iommu,
                         struct vfio_info_cap *caps)
  {
      struct vfio_iommu_type1_info_cap_migration cap_mig;

      cap_mig.header.id = VFIO_IOMMU_TYPE1_INFO_CAP_MIGRATION;
      cap_mig.header.version = 1;

      cap_mig.flags = 0;
      /* support minimum pgsize */
      cap_mig.pgsize_bitmap = (size_t)1 << __ffs(iommu->pgsize_bitmap);
      cap_mig.max_dirty_bitmap_size = DIRTY_BITMAP_SIZE_MAX;

      return vfio_info_add_capability(caps, &cap_mig.header, sizeof(cap_mig));
  }

The structure is then copied to a temporary location on the heap. At this point
it's already too late and ioctl(VFIO_IOMMU_GET_INFO) copies it to userspace
later:

  int vfio_info_add_capability(struct vfio_info_cap *caps,
                   struct vfio_info_cap_header *cap, size_t size)
  {
      struct vfio_info_cap_header *header;

      header = vfio_info_cap_add(caps, size, cap->id, cap->version);
      if (IS_ERR(header))
          return PTR_ERR(header);

      memcpy(header + 1, cap + 1, size - sizeof(*header));

      return 0;
  }

This issue was found by code inspection.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Kevin Tian <kevin.tian@intel.com>
Fixes: ad721705d0 ("vfio iommu: Add migration capability to report supported features")
Link: https://lore.kernel.org/r/20230801155352.1391945-1-stefanha@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2023-09-13 09:42:47 +02:00
arch powerpc/radix: Move some functions into #ifdef CONFIG_KVM_BOOK3S_HV_POSSIBLE 2023-09-13 09:42:47 +02:00
block block/mq-deadline: use correct way to throttling write requests 2023-09-13 09:42:42 +02:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: api - Use work queue in crypto_destroy_instance 2023-09-13 09:42:32 +02:00
Documentation media: uapi: HEVC: Add num_delta_pocs_of_ref_rps_idx field 2023-09-13 09:42:20 +02:00
drivers vfio/type1: fix cap_migration information leak 2023-09-13 09:42:47 +02:00
fs ext4: avoid potential data overflow in next_linear_group 2023-09-13 09:42:46 +02:00
include PCI: Add locking to RMW PCI Express Capability Register accessors 2023-09-13 09:42:46 +02:00
init sched/psi: Select KERNFS as needed 2023-09-13 09:42:28 +02:00
io_uring io_uring: fix drain stalls by invalid SQE 2023-09-13 09:42:43 +02:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel PCI: Allow drivers to request exclusive config regions 2023-09-13 09:42:46 +02:00
lib maple_tree: disable mas_wr_append() when other readers are possible 2023-08-30 16:11:13 +02:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm net-memcg: Fix scope of sockmem pressure indicators 2023-09-13 09:42:33 +02:00
net netrom: Deny concurrent connect(). 2023-09-13 09:42:35 +02:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples samples/bpf: fix broken map lookup probe 2023-09-13 09:42:34 +02:00
scripts kbuild: rust_is_available: fix confusion when a version appears in the path 2023-09-13 09:42:32 +02:00
security smackfs: Prevent underflow in smk_set_cipso() 2023-09-13 09:42:42 +02:00
sound ALSA: ac97: Fix possible error value of *rac97 2023-09-13 09:42:44 +02:00
tools selftests/bpf: Clean up fmod_ret in bench_rename test script 2023-09-13 09:42:33 +02:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS devlink: move code to a dedicated directory 2023-08-30 16:11:00 +02:00
Makefile kbuild: rust_is_available: remove -v option 2023-09-13 09:42:32 +02:00
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.