🇰🇷 한글 설명
Linux 커널의 drm/msm 드라이버에서 SSPP(Shared Scanout Plane Pipeline)가 준비되지 않은 상태에서 이를 검증하려고 시도할 때 발생하는 취약점입니다. 현재 평면(current plane)에 할당된 SSPP가 없는 상태에서 참조를 시도하여 커널 NULL 포인터 역참조(NULL pointer dereference)로 인한 시스템 충돌이 발생합니다.
💡 쉬운 설명
그래픽 화면을 처리하는 과정에서 아직 준비되지 않은 정보를 확인하려다 컴퓨터의 핵심 시스템(커널)이 갑자기 멈추거나 꺼지는 오류가 발생합니다. 이는 잘못된 메모리 주소를 참조하여 발생하는 소프트웨어 결함입니다.
🇺🇸 원문 (English)
In the Linux kernel, the following vulnerability has been resolved:
drm/msm: Do not validate SSPP when it is not ready
Current code will validate current plane and previous plane to
confirm they can share a SSPP with multi-rect mode. The SSPP
is already allocated for previous plane, while current plane
is not associated with any SSPP yet. Null pointer is referenced
when validating the SSPP of current plane. Skip SSPP validation
for current plane.
Unable to handle kernel NULL pointer dereference at virtual address 0000000000000020
Mem abort info:
ESR = 0x0000000096000004
EC = 0x25: DABT (current EL), IL = 32 bits
SET = 0, FnV = 0
EA = 0, S1PTW = 0
FSC = 0x04: level 0 translation fault
Data abort info:
ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
CM = 0, WnR = 0, TnD = 0, TagAccess = 0
GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
user pgtable: 4k pages, 48-bit VAs, pgdp=0000000888ac3000
[0000000000000020] pgd=0000000000000000, p4d=0000000000000000
Internal error: Oops: 0000000096000004 [#1] SMP
Modules linked in:
CPU: 4 UID: 0 PID: 1891 Comm: modetest Tainted: G S 6.15.0-rc2-g3ee3f6e1202e #335 PREEMPT
Tainted: [S]=CPU_OUT_OF_SPEC
Hardware name: SM8650 EV1 rev1 4slam 2et (DT)
pstate: 63400009 (nZCv daif +PAN -UAO +TCO +DIT -SSBS BTYPE=--)
pc : dpu_plane_is_multirect_capable+0x68/0x90
lr : dpu_assign_plane_resources+0x288/0x410
sp : ffff800093dcb770
x29: ffff800093dcb770 x28: 0000000000002000 x27: ffff000817c6c000
x26: ffff000806b46368 x25: ffff0008013f6080 x24: ffff00080cbf4800
x23: ffff000810842680 x22: ffff0008013f1080 x21: ffff00080cc86080
x20: ffff000806b463b0 x19: ffff00080cbf5a00 x18: 00000000ffffffff
x17: 707a5f657a696c61 x16: 0000000000000003 x15: 0000000000002200
x14: 00000000ffffffff x13: 00aaaaaa00aaaaaa x12: 0000000000000000
x11: ffff000817c6e2b8 x10: 0000000000000000 x9 : ffff80008106a950
x8 : ffff00080cbf48f4 x7 : 0000000000000000 x6 : 0000000000000000
x5 : 0000000000000000 x4 : 0000000000000438 x3 : 0000000000000438
x2 : ffff800082e245e0 x1 : 0000000000000008 x0 : 0000000000000000
Call trace:
dpu_plane_is_multirect_capable+0x68/0x90 (P)
dpu_crtc_atomic_check+0x5bc/0x650
drm_atomic_helper_check_planes+0x13c/0x220
drm_atomic_helper_check+0x58/0xb8
msm_atomic_check+0xd8/0xf0
drm_atomic_check_only+0x4a8/0x968
drm_atomic_commit+0x50/0xd8
drm_atomic_helper_update_plane+0x140/0x188
__setplane_atomic+0xfc/0x148
drm_mode_setplane+0x164/0x378
drm_ioctl_kernel+0xc0/0x140
drm_ioctl+0x20c/0x500
__arm64_sys_ioctl+0xbc/0xf8
invoke_syscall+0x50/0x120
el0_svc_common.constprop.0+0x48/0xf8
do_el0_svc+0x28/0x40
el0_svc+0x30/0xd0
el0t_64_sync_handler+0x144/0x168
el0t_64_sync+0x198/0x1a0
Code: b9402021 370fffc1 f9401441 3707ff81 (f94010a1)
---[ end trace 0000000000000000 ]---
Patchwork: https://patchwork.freedesktop.org/patch/669224/
📍 영향받는 시스템
Linux kernel (drm/msm driver), specifically versions around 6.15.0-rc2 and related SM8650 hardware platforms
⚔️ 공격 벡터
로컬 공격자가 특수하게 조작된 DRM IOCTL 호출을 통해 커널의 NULL 포인터 역참조를 유도하여 시스템을 중단(DoS)시킬 수 있음
🛡️ 대응 방법
Linux 커널을 최신 패치가 적용된 버전으로 업데이트하거나, 해당 드라이버의 SSPP 검증 로직이 수정된 패치를 적용해야 함
🔧 검증 코드
출력된 커널 버전이 취약점이 해결된 패치 버전(patch 669224 적용 버전)인지 확인하십시오.