CVE-2026-98517 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
drm/nouveau/uvmm: fix UAF in nouveau_uvmm_sm when BO is in TTM_PL_SYSTEM
nouveau_uvmm_sm() calls op_map(), which passes bo->resource through nouveau_mem() to nouveau_uvma_map(). nouveau_uvmm_vmm_map() then reads mem->mem.type.
But this is only valid when bo->resource is backed by struct nouveau_mem, as is the case for VRAM and TT resources. If the BO is left in TTM_PL_SYSTEM, bo->resource is only a struct ttm_resource. Treating it as struct nouveau_mem makes the mem->mem.type read past the end of the resource, causing a KASAN: slab-use-after-free Read in nouveau_uvmm_sm report:
BUG: KASAN: slab-use-after-free in nouveau_uvmm_vmm_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:152 [inline]
BUG: KASAN: slab-use-after-free in nouveau_uvma_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:199 [inline]
BUG: KASAN: slab-use-after-free in op_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:849 [inline]
BUG: KASAN: slab-use-after-free in nouveau_uvmm_sm.constprop.0+0x6ab/0x900 drivers/gpu/drm/nouveau/nouveau_uvmm.c:903 Read of size 1 at addr ffff888127d3e3a0 by task kworker/0:1/11
CPU: 0 UID: 0 PID: 11 Comm: kworker/0:1 Not tainted 7.2.0 #5 PREEMPT(lazy) Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 Workqueue: nouveau_sched_wq_2224 drm_sched_run_job_work Call Trace: <TASK> __dump_stack lib/dump_stack.c:94 [inline]
dump_stack_lvl+0x95/0xe0 lib/dump_stack.c:120 print_address_description mm/kasan/report.c:378 [inline]
print_report+0xcb/0x5a0 mm/kasan/report.c:482 kasan_report+0xca/0x100 mm/kasan/report.c:595 nouveau_uvmm_vmm_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:152 [inline]
nouveau_uvma_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:199 [inline]
op_map drivers/gpu/drm/nouveau/nouveau_uvmm.c:849 [inline]
nouveau_uvmm_sm.constprop.0+0x6ab/0x900 drivers/gpu/drm/nouveau/nouveau_uvmm.c:903 nouveau_uvmm_sm_unmap drivers/gpu/drm/nouveau/nouveau_uvmm.c:932 [inline]
nouveau_uvmm_bind_job_run+0xd6/0x250 drivers/gpu/drm/nouveau/nouveau_uvmm.c:1532 nouveau_job_run drivers/gpu/drm/nouveau/nouveau_sched.c:350 [inline]
nouveau_sched_run_job+0x62/0xd0 drivers/gpu/drm/nouveau/nouveau_sched.c:364 drm_sched_run_job_work+0x356/0xa10 drivers/gpu/drm/scheduler/sched_main.c:1061 process_one_work+0x8a5/0x1900 kernel/workqueue.c:3322 process_scheduled_works kernel/workqueue.c:3405 [inline]
worker_thread+0x5dd/0xd80 kernel/workqueue.c:3486 kthread+0x31d/0x420 kernel/kthread.c:436 ret_from_fork+0x662/0x940 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 </TASK>
Allocated by task 2224 on cpu 0 at 66.550027s: kasan_save_stack+0x24/0x50 mm/kasan/common.c:57 kasan_save_track+0x17/0x60 mm/kasan/common.c:78 poison_kmalloc_redzone mm/kasan/common.c:398 [inline]
__kasan_kmalloc+0xaa/0xb0 mm/kasan/common.c:415 kasan_kmalloc include/linux/kasan.h:263 [inline]
__do_kmalloc_node mm/slub.c:5334 [inline]
__kmalloc_noprof+0x304/0x7c0 mm/slub.c:5359 _kmalloc_noprof include/linux/slab.h:992 [inline]
dma_resv_list_alloc+0x27/0x90 drivers/dma-buf/dma-resv.c:106 dma_resv_reserve_fences+0x60e/0xa30 drivers/dma-buf/dma-resv.c:205 ttm_bo_alloc_resource+0x12c/0xbd0 drivers/gpu/drm/ttm/ttm_bo.c:721 ttm_bo_validate+0x1bc/0x4a0 drivers/gpu/drm/ttm/ttm_bo.c:856 ttm_bo_init_reserved+0x2c3/0x570 drivers/gpu/drm/ttm/ttm_bo.c:970 nouveau_bo_init+0x159/0x2c0 drivers/gpu/drm/nouveau/nouveau_bo.c:359 nouveau_gem_new+0x234/0x5f0 drivers/gpu/drm/nouveau/nouveau_gem.c:272 nouveau_gem_ioctl_new+0x1eb/0x420 drivers/gpu/drm/nouveau/nouveau_gem.c:352 drm_ioctl_kernel+0x192/0x350 drivers/gpu/drm/drm_ioctl.c:817 drm_ioctl+0x4f8/0xb40 drivers/gpu/drm/drm_ioctl.c:914 nouveau_drm_ioctl+0xea/0x2c0 drivers/gpu/drm/nouveau/nouveau_drm.c:1338 vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:597 [inline]
__se_sys_ioctl fs/ioctl.c:583 [inline]
__x64_sys_ioctl+0x180/0x1d0 fs/ioctl.c:583 do_syscall_x64 ar ---truncated---
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Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel driver for NVIDIA graphics hardware, specifically the nouveau subsystem within the Direct Rendering Manager (DRM), contains a critical memory safety vulnerability identified as a use-after-free error. This flaw resides in the Unified Virtual Memory Management (UVMM) implementation and is triggered when buffer objects are allocated with system memory placement rather than video RAM or translation table resources. The root cause lies in an incorrect type casting assumption within the nouveau_uvmm_sm function, which invokes op_map to process a buffer object resource. During this operation, the code passes bo->resource through nouveau_mem() to reach nouveau_uvma_map and subsequently nouveau_uvmm_vmm_map. These functions expect the underlying data structure to be of type struct nouveau_mem, which contains specific fields such as mem.type that are essential for mapping operations. However, when a buffer object is placed in TTM_PL_SYSTEM, meaning it resides in standard system RAM managed by the Translation Table Maps (TTM) subsystem rather than GPU-specific memory pools, bo->resource points to a generic struct ttm_resource instead of the extended nouveau_mem structure.
This mismatch leads to an out-of-bounds read where the kernel attempts to access mem->mem.type at an offset that is valid for struct nouveau_mem but invalid for struct ttm_resource. Because these two structures have different memory layouts and sizes, reading past the end of the smaller ttm_resource object results in accessing uninitialized or freed memory regions. This specific error manifests as a KASAN slab-use-after-free read report, indicating that the kernel has accessed memory that is no longer validly mapped to the current context. The vulnerability can be exploited by local users who have permission to create buffer objects via DRM ioctls, potentially leading to information disclosure or system instability depending on what data resides in the adjacent memory space. In severe cases, this could facilitate further exploitation chains if an attacker can control the contents of the accessed memory region.
From a technical classification perspective, this vulnerability aligns with CWE-416, Use After Free, as it involves accessing memory after its lifetime has ended or misinterpreting the type and size of allocated structures leading to invalid access patterns similar to out-of-bounds reads associated with CWE-125. In terms of attack vectors, this falls under ATT&CK technique T1059, Command and Scripting Interpreter, specifically through local execution via kernel module interactions, although it is primarily a memory corruption issue rather than direct command injection. The impact includes potential denial of service due to kernel panic or crash, as evidenced by the stack trace showing workqueue processing failures in nouveau_sched_run_job_work. Additionally, there is a risk of privilege escalation if an attacker can leverage the leaked information to bypass security checks within the DRM subsystem.
Mitigation strategies primarily involve applying the upstream Linux kernel patch that resolves this issue by adding proper type checking before casting bo->resource to struct nouveau_mem. Developers and system administrators should ensure their systems are updated with the latest stable kernel versions where this fix is included. For environments unable to update immediately, restricting access to DRM ioctls for untrusted users or disabling the specific GPU functionality that triggers buffer object creation in TTM_PL_SYSTEM mode can reduce exposure. It is also recommended to monitor system logs for KASAN reports which indicate memory corruption issues within kernel modules, allowing for rapid identification and response to potential exploitation attempts targeting this driver component.