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android/kernel/common/4a2a41bddacb3e9b3b908b61d057c1f1d1669c45
commit
4a2a41bddacb3e9b3b908b61d057c1f1d1669c45
[log]
author
T.J. Mercier <tjmercier@google.com>
Tue Apr 07 12:27:42 2026 -0700
committer
T.J. Mercier <tjmercier@google.com>
Fri Apr 10 10:04:25 2026 -0700
tree
06afd17f029e3792a233bce3d662fbfbaf9754db
parent
46ef1aec3ce01f374a4911364a41c044b644048f [diff]
ANDROID: Compute dmabuf info for forks from scratch

For forks (!CLONE_VM && !CLONE_FILES) the child's task_dma_buf_info is
created as a copy of the parent's in dup_dma_buf_info. This assumes that
the parent and child share all FD and VMA dmabuf references, however
conditions can exist that result in dmabuf references from a parent to
not propagate to a child via fork:

* madvise(MADV_DONTFORK) (i.e. VM_DONTCOPY) on a dmabuf VMA
* Raciness between copy_files / copy_mm and copy_dmabuf_info where a
  parent thread closes FDs or unmaps

This results in incorrect accounting information in the child, and
potentially a UAF in dup_dma_buf_info when dereferencing a pointer to a
freed dmabuf.

Fix this by scanning the mm_struct and files_struct for all dmabuf
references in the child, and accounting each against the child's new
task_dma_buf_info.

Fixes: 060742b3d06d ("ANDROID: Track per-process dmabuf RSS")
Bug: 424648392
Change-Id: I891edd2956419c2952c3e3ea57a92cb3b25b903a
Signed-off-by: T.J. Mercier <tjmercier@google.com>
1 file changed
tree: 06afd17f029e3792a233bce3d662fbfbaf9754db
  1. android/
  2. arch/
  3. bazel/
  4. block/
  5. certs/
  6. crypto/
  7. Documentation/
  8. drivers/
  9. fs/
  10. include/
  11. init/
  12. io_uring/
  13. ipc/
  14. kernel/
  15. lib/
  16. LICENSES/
  17. mm/
  18. net/
  19. rust/
  20. samples/
  21. scripts/
  22. security/
  23. sound/
  24. tools/
  25. usr/
  26. virt/
  27. .clang-format
  28. .cocciconfig
  29. .get_maintainer.ignore
  30. .gitattributes
  31. .gitignore
  32. .mailmap
  33. .rustfmt.toml
  34. BUILD.bazel
  35. build.config.aarch64
  36. build.config.allmodconfig
  37. build.config.allmodconfig.aarch64
  38. build.config.allmodconfig.arm
  39. build.config.allmodconfig.x86_64
  40. build.config.amlogic
  41. build.config.arm
  42. build.config.common
  43. build.config.constants
  44. build.config.crashdump
  45. build.config.crashdump.aarch64
  46. build.config.crashdump.x86_64
  47. build.config.db845c
  48. build.config.gki
  49. build.config.gki-debug.aarch64
  50. build.config.gki-debug.x86_64
  51. build.config.gki.aarch64
  52. build.config.gki.aarch64.fips140
  53. build.config.gki.riscv64
  54. build.config.gki.x86_64
  55. build.config.gki_kasan
  56. build.config.gki_kasan.aarch64
  57. build.config.gki_kasan.x86_64
  58. build.config.gki_kprobes
  59. build.config.gki_kprobes.aarch64
  60. build.config.gki_kprobes.x86_64
  61. build.config.khwasan
  62. build.config.microdroid
  63. build.config.microdroid.aarch64
  64. build.config.microdroid.x86_64
  65. build.config.riscv64
  66. build.config.rockchip
  67. build.config.rockpi4
  68. build.config.wonder
  69. build.config.x86_64
  70. COPYING
  71. CREDITS
  72. Kbuild
  73. Kconfig
  74. Kconfig.ext
  75. MAINTAINERS
  76. Makefile
  77. modules.bzl
  78. OWNERS
  79. README
  80. README.md
README.md

How do I submit patches to Android Common Kernels

  1. BEST: Make all of your changes to upstream Linux. If appropriate, backport to the stable releases. These patches will be merged automatically in the corresponding common kernels. If the patch is already in upstream Linux, post a backport of the patch that conforms to the patch requirements below.

    • Do not send patches upstream that contain only symbol exports. To be considered for upstream Linux, additions of EXPORT_SYMBOL_GPL() require an in-tree modular driver that uses the symbol -- so include the new driver or changes to an existing driver in the same patchset as the export.
    • When sending patches upstream, the commit message must contain a clear case for why the patch is needed and beneficial to the community. Enabling out-of-tree drivers or functionality is not not a persuasive case.

  2. LESS GOOD: Develop your patches out-of-tree (from an upstream Linux point-of-view). Unless these are fixing an Android-specific bug, these are very unlikely to be accepted unless they have been coordinated with kernel-team@android.com. If you want to proceed, post a patch that conforms to the patch requirements below.

Common Kernel patch requirements

  • All patches must conform to the Linux kernel coding standards and pass scripts/checkpatch.pl
  • Patches shall not break gki_defconfig or allmodconfig builds for arm, arm64, x86, x86_64 architectures (see https://source.android.com/setup/build/building-kernels)
  • If the patch is not merged from an upstream branch, the subject must be tagged with the type of patch: UPSTREAM:, BACKPORT:, FROMGIT:, FROMLIST:, or ANDROID:.
  • All patches must have a Change-Id: tag (see https://gerrit-review.googlesource.com/Documentation/user-changeid.html)
  • If an Android bug has been assigned, there must be a Bug: tag.
  • All patches must have a Signed-off-by: tag by the author and the submitter

Additional requirements are listed below based on patch type

Requirements for backports from mainline Linux: UPSTREAM:, BACKPORT:

  • If the patch is a cherry-pick from Linux mainline with no changes at all
    • tag the patch subject with UPSTREAM:.
    • add upstream commit information with a (cherry picked from commit ...) line
    • Example:
      • if the upstream commit message is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        UPSTREAM: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch requires any changes from the upstream version, tag the patch with BACKPORT: instead of UPSTREAM:.
    • use the same tags as UPSTREAM:
    • add comments about the changes under the (cherry picked from commit ...) line
    • Example:
        BACKPORT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        (cherry picked from commit c31e73121f4c1ec41143423ac6ce3ce6dafdcec1)
        [joe: Resolved minor conflict in drivers/foo/bar.c ]
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for other backports: FROMGIT:, FROMLIST:,

  • If the patch has been merged into an upstream maintainer tree, but has not yet been merged into Linux mainline
    • tag the patch subject with FROMGIT:
    • add info on where the patch came from as (cherry picked from commit <sha1> <repo> <branch>). This must be a stable maintainer branch (not rebased, so don't use linux-next for example).
    • if changes were required, use BACKPORT: FROMGIT:
    • Example:
      • if the commit message in the maintainer tree is
        important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>
  • then Joe Smith would upload the patch for the common kernel as
        FROMGIT: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        (cherry picked from commit 878a2fd9de10b03d11d2f622250285c7e63deace
         https://git.kernel.org/pub/scm/linux/kernel/git/foo/bar.git test-branch)
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch has been submitted to LKML, but not accepted into any maintainer tree
    • tag the patch subject with FROMLIST:
    • add a Link: tag with a link to the submittal on lore.kernel.org
    • add a Bug: tag with the Android bug (required for patches not accepted into a maintainer tree)
    • if changes were required, use BACKPORT: FROMLIST:
    • Example:
        FROMLIST: important patch from upstream

        This is the detailed description of the important patch

        Signed-off-by: Fred Jones <fred.jones@foo.org>

        Bug: 135791357
        Link: https://lore.kernel.org/lkml/20190619171517.GA17557@someone.com/
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>

Requirements for Android-specific patches: ANDROID:

  • If the patch is fixing a bug to Android-specific code
    • tag the patch subject with ANDROID:
    • add a Fixes: tag that cites the patch with the bug
    • Example:
        ANDROID: fix android-specific bug in foobar.c

        This is the detailed description of the important fix

        Fixes: 1234abcd2468 ("foobar: add cool feature")
        Change-Id: I4caaaa566ea080fa148c5e768bb1a0b6f7201c01
        Signed-off-by: Joe Smith <joe.smith@foo.org>
  • If the patch is a new feature
    • tag the patch subject with ANDROID:
    • add a Bug: tag with the Android bug (required for android-specific features)