6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Chris Bainbridge chris.bainbridge@gmail.com
commit 8ec0fbb28d049273bfd4f1e7a5ae4c74884beed3 upstream.
Fix an oops in ttm_bo_delayed_delete which results from dererencing a dangling pointer:
Oops: general protection fault, probably for non-canonical address 0x6b6b6b6b6b6b6b7b: 0000 [#1] PREEMPT SMP CPU: 4 UID: 0 PID: 1082 Comm: kworker/u65:2 Not tainted 6.14.0-rc4-00267-g505460b44513-dirty #216 Hardware name: LENOVO 82N6/LNVNB161216, BIOS GKCN65WW 01/16/2024 Workqueue: ttm ttm_bo_delayed_delete [ttm] RIP: 0010:dma_resv_iter_first_unlocked+0x55/0x290 Code: 31 f6 48 c7 c7 00 2b fa aa e8 97 bd 52 ff e8 a2 c1 53 00 5a 85 c0 74 48 e9 88 01 00 00 4c 89 63 20 4d 85 e4 0f 84 30 01 00 00 <41> 8b 44 24 10 c6 43 2c 01 48 89 df 89 43 28 e8 97 fd ff ff 4c 8b RSP: 0018:ffffbf9383473d60 EFLAGS: 00010202 RAX: 0000000000000001 RBX: ffffbf9383473d88 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffffbf9383473d78 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 6b6b6b6b6b6b6b6b R13: ffffa003bbf78580 R14: ffffa003a6728040 R15: 00000000000383cc FS: 0000000000000000(0000) GS:ffffa00991c00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000758348024dd0 CR3: 000000012c259000 CR4: 0000000000f50ef0 PKRU: 55555554 Call Trace: <TASK> ? __die_body.cold+0x19/0x26 ? die_addr+0x3d/0x70 ? exc_general_protection+0x159/0x460 ? asm_exc_general_protection+0x27/0x30 ? dma_resv_iter_first_unlocked+0x55/0x290 dma_resv_wait_timeout+0x56/0x100 ttm_bo_delayed_delete+0x69/0xb0 [ttm] process_one_work+0x217/0x5c0 worker_thread+0x1c8/0x3d0 ? apply_wqattrs_cleanup.part.0+0xc0/0xc0 kthread+0x10b/0x240 ? kthreads_online_cpu+0x140/0x140 ret_from_fork+0x40/0x70 ? kthreads_online_cpu+0x140/0x140 ret_from_fork_asm+0x11/0x20 </TASK>
The cause of this is:
- drm_prime_gem_destroy calls dma_buf_put(dma_buf) which releases the reference to the shared dma_buf. The reference count is 0, so the dma_buf is destroyed, which in turn decrements the corresponding amdgpu_bo reference count to 0, and the amdgpu_bo is destroyed - calling drm_gem_object_release then dma_resv_fini (which destroys the reservation object), then finally freeing the amdgpu_bo.
- nouveau_bo obj->bo.base.resv is now a dangling pointer to the memory formerly allocated to the amdgpu_bo.
- nouveau_gem_object_del calls ttm_bo_put(&nvbo->bo) which calls ttm_bo_release, which schedules ttm_bo_delayed_delete.
- ttm_bo_delayed_delete runs and dereferences the dangling resv pointer, resulting in a general protection fault.
Fix this by moving the drm_prime_gem_destroy call from nouveau_gem_object_del to nouveau_bo_del_ttm. This ensures that it will be run after ttm_bo_delayed_delete.
Signed-off-by: Chris Bainbridge chris.bainbridge@gmail.com Suggested-by: Christian König christian.koenig@amd.com Fixes: 22b33e8ed0e3 ("nouveau: add PRIME support") Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3937 Cc: Stable@vger.kernel.org Signed-off-by: Danilo Krummrich dakr@kernel.org Link: https://patchwork.freedesktop.org/patch/msgid/Z-P4epVK8k7tFZ7C@debian.local Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/gpu/drm/nouveau/nouveau_bo.c | 3 +++ drivers/gpu/drm/nouveau/nouveau_gem.c | 3 --- 2 files changed, 3 insertions(+), 3 deletions(-)
--- a/drivers/gpu/drm/nouveau/nouveau_bo.c +++ b/drivers/gpu/drm/nouveau/nouveau_bo.c @@ -144,6 +144,9 @@ nouveau_bo_del_ttm(struct ttm_buffer_obj nouveau_bo_del_io_reserve_lru(bo); nv10_bo_put_tile_region(dev, nvbo->tile, NULL);
+ if (bo->base.import_attach) + drm_prime_gem_destroy(&bo->base, bo->sg); + /* * If nouveau_bo_new() allocated this buffer, the GEM object was never * initialized, so don't attempt to release it. --- a/drivers/gpu/drm/nouveau/nouveau_gem.c +++ b/drivers/gpu/drm/nouveau/nouveau_gem.c @@ -87,9 +87,6 @@ nouveau_gem_object_del(struct drm_gem_ob return; }
- if (gem->import_attach) - drm_prime_gem_destroy(gem, nvbo->bo.sg); - ttm_bo_put(&nvbo->bo);
pm_runtime_mark_last_busy(dev);