🇰🇷 한글 설명
Linux 커널의 nouveau 드라이버에서 ttm_bo_delayed_delete 함수가 이미 해제된 메모리 주소(dangling pointer)를 참조하여 발생하는 오류입니다. 이로 인해 시스템에 General Protection Fault가 발생하며 커널 패닉(Oops)이 유발될 수 있습니다.
💡 쉬운 설명
컴퓨터 그래픽 카드를 관리하는 프로그램이 이미 삭제된 메모리 정보를 다시 사용하려고 시도하다가 시스템이 멈추거나 오류가 발생하는 문제입니다. 메모리 정리 순서가 잘못되어 발생하는 기술적 결함입니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau: prime: fix ttm_bo_delayed_delete oops
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.
📍 영향받는 시스템
Linux kernel (nouveau DRM driver, specifically versions involving ttm_bo_delayed_delete)
⚔️ 공격 벡터
Local (사용자가 특정 그래픽 자원 해제 시나리오를 유도하여 커널 패닉 유발 가능)
🛡️ 대응 방법
Linux 커널을 최신 보안 패치가 적용된 버전으로 업데이트하여 drm_prime_gem_destroy 호출 순서를 수정해야 합니다.
🔧 검증 코드
출력된 커널 버전이 취약점이 해결된 최신 패치 버전인지 확인합니다.