Re: [PATCH v9 00/10] Fix missing fops.owner in Rust DRM/misc abstractions

[Alvin Sun <alvin.sun@linux.dev>]

Hi Miguel,

Back in v3, Gary suggested this series go via the rust tree.
Would you be happy with that, or would you prefer a different
path? If so, is there anything else needed from my side?

Best regards,
Alvin

On 7/23/26 10:10, Alvin Sun wrote:
> During tyr debugfs development, a kernel NULL pointer dereference was
> encountered after `rmmod tyr` while gnome-shell still held /dev/card1 open:
>
> ```
>    [158827.868132] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
>    [158827.868918] Mem abort info:
>    [158827.869177]   ESR = 0x0000000086000004
>    [158827.869519]   EC = 0x21: IABT (current EL), IL = 32 bits
>    [158827.870000]   SET = 0, FnV = 0
>    [158827.870281]   EA = 0, S1PTW = 0
>    [158827.870571]   FSC = 0x04: level 0 translation fault
>    [158827.871043] user pgtable: 4k pages, 48-bit VAs, pgdp=0000000108dec000
>    [158827.871623] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
>    [158827.872242] Internal error: Oops: 0000000086000004 [#1]  SMP
>    [158827.872246] Modules linked in: tyr sunrpc snd_soc_simple_card rk805_pwrkey snd_soc_simple_card_utils rtw88_8822bu display_connector rtw88_usb rtw88_8822b snd_soc_rockchip_i2s_tdm snd_soc_hdmi_codec
>    rtw88_core]
>    [158827.872337] CPU: 4 UID: 1000 PID: 11276 Comm: gnome-s:disk$0 Tainted: G                 N  7.1.0-rc1+ #331 PREEMPT
>    [158827.880534] Tainted: [N]=TEST
>    [158827.880535] Hardware name: FriendlyElec NanoPi R6C/NanoPi R6C, BIOS v1.1 04/09/2025
>    [158827.880538] pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>    [158827.880542] pc : 0x0
>    [158827.880547] lr : _RNvNtCs257m05FHVbX_3tyr2vm8pt_unmap+0x8c/0x12c [tyr]
>    [158827.880578] sp : ffff800083c236b0
>    [158827.880579] x29: ffff800083c236d0 x28: ffff00013f8a0000 x27: 0000000000000000
>    [158827.880585] x26: 000000000000007c x25: ffff000108e6ed80 x24: 0000000000401000
>    [158827.880590] x23: 0000000000000000 x22: 0000000040000000 x21: 0000000000001000
>    [158827.880595] x20: ffff00010f778138 x19: 0000000000400000 x18: 00000000ffffffff
>    [158827.880600] x17: 000000040044ffff x16: 045000f2b5503510 x15: 0720072007200720
>    [158827.880606] x14: 0720072007200720 x13: 0000000000401000 x12: 0000000000400000
>    [158827.880611] x11: ffff800083c239d0 x10: ffff000141e4fd88 x9 : 0000000000000000
>    [158827.880615] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000400000
>    [158827.880620] x5 : ffff00013f8a0000 x4 : 0000000000000000 x3 : 0000000000000001
>    [158827.880625] x2 : 0000000000001000 x1 : 0000000000400000 x0 : ffff00010f778138
>    [158827.880630] Call trace:
>    [158827.880632]  0x0 (P)
>    [158827.880635]  _RNvXs6_NtCs257m05FHVbX_3tyr2vmNtB5_9GpuVmDataNtNtNtCsgmSOfgXi5CZ_6kernel3drm5gpuvm11DriverGpuVm13sm_step_unmap+0x3c/0x120 [tyr]
>    [158827.891166]  _RNvMs4_NtNtNtCsgmSOfgXi5CZ_6kernel3drm5gpuvm6sm_opsINtB7_5GpuVmNtNtCs257m05FHVbX_3tyr2vm9GpuVmDataE13sm_step_unmapB13_+0x18/0x34 [tyr]
>    [158827.891187]  op_unmap_cb+0x78/0xb0
>    [158827.891196]  __drm_gpuvm_sm_unmap+0x18c/0x1b4
>    [158827.891204]  drm_gpuvm_sm_unmap+0x38/0x4c
>    [158827.891209]  _RNvMs5_NtCs257m05FHVbX_3tyr2vmNtB5_2Vm7exec_op+0x1cc/0x254 [tyr]
>    [158827.894085]  _RNvMs5_NtCs257m05FHVbX_3tyr2vmNtB5_2Vm11unmap_range+0x124/0x188 [tyr]
>    [158827.894105]  _RINvNtCs5hGKnPbRUFW_4core3ptr13drop_in_placeNtNtCs257m05FHVbX_3tyr3gem8KernelBoEBK_+0x44/0xd8 [tyr]
>    [158827.894125]  _RINvNtCs5hGKnPbRUFW_4core3ptr13drop_in_placeINtNtNtCsgmSOfgXi5CZ_6kernel5alloc4kvec3VecNtNtCs257m05FHVbX_3tyr2fw7SectionNtNtBL_9allocator7KmallocEEB1r_+0x3c/0x100 [tyr]
>    [158827.894147]  _RINvNtCs5hGKnPbRUFW_4core3ptr13drop_in_placeINtNtNtCsgmSOfgXi5CZ_6kernel4sync3arc3ArcNtNtCs257m05FHVbX_3tyr2fw8FirmwareEEB1p_+0x94/0x190 [tyr]
>    [158827.894167]  _RNvMs4_NtNtCsgmSOfgXi5CZ_6kernel3drm6deviceINtB5_6DeviceNtNtCs257m05FHVbX_3tyr6driver12TyrDrmDriverE7releaseBW_+0x30/0x98 [tyr]
>    [158827.899550]  drm_dev_put.part.0+0x88/0xc0
>    [158827.899557]  drm_minor_release+0x18/0x28
>    [158827.899562]  drm_release+0x144/0x170
>    [158827.899567]  __fput+0xe4/0x30c
>    [158827.899573]  ____fput+0x14/0x20
>    [158827.899579]  task_work_run+0x7c/0xe8
>    [158827.899586]  do_exit+0x2a8/0xac4
>    [158827.899590]  do_group_exit+0x34/0x90
>    [158827.899594]  get_signal+0xaac/0xabc
>    [158827.899599]  arch_do_signal_or_restart+0x90/0x3e8
>    [158827.899606]  exit_to_user_mode_loop+0x140/0x1d0
>    [158827.899613]  el0_svc+0x2f4/0x2f8
>    [158827.899620]  el0t_64_sync_handler+0xa0/0xe4
>    [158827.899627]  el0t_64_sync+0x198/0x19c
>    [158827.899632] ---[ end trace 0000000000000000 ]---
> ```
>
> The root cause: `fops.owner` was `NULL` in Rust DRM drivers, so the kernel
> never blocked module unloading while file descriptors were open. This leads to
> use-after-free when drm_release (or other fops) is called on freed module code.
>
> The series moves `THIS_MODULE` into the `ModuleMetadata` as a const, threads it
> through `#[vtable]` to set `fops.owner` in DRM/miscdevice, and updates configfs
> and rnull to use `this_module::<LocalModule>()`.
>
> Assisted-by: opencode:glm-5.2
> Signed-off-by: Alvin Sun <alvin.sun@linux.dev>
> ---
> Changes in v9:
> - Rename the binder commit prefix from `rust: binder:` to `rust_binder:`
>    to match the in-tree module name.
> - Link to v8: https://lore.kernel.org/r/20260713-fix-fops-owner-v8-0-2495cfa82d47@linux.dev
>
> Changes in v8:
> - Remove unused `crate::LocalModule` import in rnull configfs.
> - Link to v7: https://lore.kernel.org/r/20260627-fix-fops-owner-v7-0-33cd3990edf0@linux.dev
>
> Changes in v7:
> - Use `crate::LocalModule` in `configfs_attrs!` and silence `clippy::crate_in_macro_def`, per Gary's review.
> - Link to v6: https://lore.kernel.org/r/20260624-fix-fops-owner-v6-0-5295e333cb3e@linux.dev
>
> Changes in v6:
> - Update MAINTAINERS to cover the new `rust/kernel/module.rs`.
> - Link to v5: https://lore.kernel.org/r/20260624-fix-fops-owner-v5-0-aa1cba242f05@linux.dev
>
> Changes in v5:
> - Add `#[inline]` to the `this_module()` helper.
> - Fix configfs doc comment to reference `crate::LocalModule` instead of
>    bare `LocalModule`.
> - Link to v4: https://lore.kernel.org/r/20260623-fix-fops-owner-v4-0-0daf5f077d5c@linux.dev
>
> Changes in v4:
> - Move module-related types into a new `rust/kernel/module.rs`.
> - Migrate binder from the `module!`-generated `THIS_MODULE` static to
>    `this_module::<LocalModule>()`.
> - Reorganise the series so that every commit builds independently, and
>    drop the legacy `THIS_MODULE` static once all users are migrated.
> - Link to v3: https://lore.kernel.org/r/20260622-fix-fops-owner-v3-0-49d45cb37032@linux.dev
>
> Changes in v3:
> - Renamed vtable associated type `ThisModule` to `OwnerModule`
> - Added `this_module()` helper for ergonomic `THIS_MODULE` access
> - Refined vtable macro implementation: one-liner detection and single `defined_items` set
> - Reordered commits to place doctest fallback before vtable auto-insert
> - Link to v2: https://lore.kernel.org/r/20260521-fix-fops-owner-v2-0-fd99079c5a04@linux.dev
>
> Changes in v2:
> - Merged old `static THIS_MODULE` and v1's `MODULE_PTR` into a single
>    `ModuleMetadata::THIS_MODULE` const
> - `#[vtable]` macro now auto-inserts `type ThisModule`, removing all per-driver
>    manual patches from v1
> - Added configfs & rnull usage site updates and doctest `LocalModule` fallback
> - Link to v1: https://lore.kernel.org/r/20260519-fix-fops-owner-v1-0-2ded9830da14@linux.dev
>
> ---
> Alvin Sun (10):
>        rust: module: move module types into `module.rs`
>        rust: module: add `THIS_MODULE` const to `ModuleMetadata` trait
>        rust: doctest: add LocalModule fallback for #[vtable] ThisModule
>        rust: macros: auto-insert OwnerModule in #[vtable]
>        rust: drm: set fops.owner from driver module pointer
>        rust: miscdevice: set fops.owner from driver module pointer
>        rust: configfs: use `LocalModule` for `THIS_MODULE`
>        rust_binder: use `LocalModule` for `THIS_MODULE`
>        rust: macros: remove `THIS_MODULE` static from `module!`
>        rust: module: update MAINTAINERS to cover module.rs
>
>   MAINTAINERS                                |  2 +-
>   drivers/android/binder/rust_binder_main.rs |  3 +-
>   drivers/block/rnull/configfs.rs            |  5 +-
>   rust/kernel/auxiliary.rs                   |  2 +-
>   rust/kernel/configfs.rs                    |  9 ++--
>   rust/kernel/drm/device.rs                  |  3 +-
>   rust/kernel/drm/gem/mod.rs                 |  4 +-
>   rust/kernel/i2c.rs                         |  2 +-
>   rust/kernel/lib.rs                         | 75 +++-------------------------
>   rust/kernel/miscdevice.rs                  |  4 +-
>   rust/kernel/module.rs                      | 80 ++++++++++++++++++++++++++++++
>   rust/kernel/net/phy.rs                     |  6 ++-
>   rust/kernel/pci.rs                         |  2 +-
>   rust/kernel/platform.rs                    |  2 +-
>   rust/kernel/usb.rs                         |  2 +-
>   rust/macros/lib.rs                         |  6 +++
>   rust/macros/module.rs                      | 34 ++++++-------
>   rust/macros/vtable.rs                      | 41 +++++++++++++--
>   scripts/rustdoc_test_gen.rs                | 16 ++++++
>   19 files changed, 189 insertions(+), 109 deletions(-)
> ---
> base-commit: b7e5ac83cb16f7ffd11dc23736f84276602100ed
> change-id: 20260519-fix-fops-owner-e3a77bb27c6c
> prerequisite-change-id: 20260519-miscdev-use-format-9ab7e83b1c11:v3
> prerequisite-patch-id: 405b334ff0d48ad350014f05a2321bdbaa025400
> prerequisite-patch-id: 604b631c81d5423f4ebb2e12ba2d22e9ce371bfc
> prerequisite-patch-id: cb550d94cefe01920e0d3ced2b2bcbecd76f3907
> prerequisite-patch-id: 3bc830839742591460cb86d9472c04f4686dc600
> prerequisite-patch-id: 571058244bc8c7088638d2e3225713011246c7e9
> prerequisite-patch-id: 347c5a3c6dbef9832bfce8419fc23e6e08ba477f
> prerequisite-patch-id: 3e202d988b56b88446f7535e90d3f00cf5f15701
>
> Best regards,