Danilo Krummrich
2025-Mar-28 10:59 UTC
[PATCH v3] drm/nouveau: prime: fix ttm_bo_delayed_delete oops
On Wed, Mar 26, 2025 at 12:52:10PM +0000, Chris Bainbridge wrote:> 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 at gmail.com> > Suggested-by: Christian K?nig <christian.koenig at amd.com> > Fixes: 22b33e8ed0e3 ("22b33e8ed0e3nouveau: add PRIME support") > Closes: https://gitlab.freedesktop.org/drm/amd/-/issues/3937 > Cc: <Stable at vger.kernel.org>Applied to drm-misc-fixes, thanks! [ Fixed up the Fixes: tag, where the commit hash is repeated in the commit subject. ]