Description
In the Linux kernel, the following vulnerability has been resolved:

drm/nouveau: don't bump pin count on failed re-pin in nouveau_bo_pin_locked()

nouveau_bo_pin_locked() checks whether an already pinned BO is in a
memory domain compatible with a new pin request. When the domains are
incompatible, it sets -EBUSY but still calls ttm_bo_pin() before
returning.

Callers treat a failed nouveau_bo_pin() as not having acquired a new pin,
so the extra pin count is never decreased by a matching unpin.
This triggers the warning in ttm_bo_release():

WARN_ON_ONCE(bo->pin_count);

Found when fuzzing the nouveau driver with a modified Syzkaller:

WARNING: drivers/gpu/drm/ttm/ttm_bo.c:256 at ttm_bo_release+0x827/0x9e0 drivers/gpu/drm/ttm/ttm_bo.c:256, CPU#1: syz.3.24/2212
Modules linked in:
CPU: 1 UID: 0 PID: 2212 Comm: syz.3.24 Not tainted 7.2.0 #24 PREEMPT(lazy)
nouveau 0000:01:00.0: gsp:msg fn:103 len:0x40/0x20 res:0x19 resp:0x19
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:ttm_bo_release+0x827/0x9e0 drivers/gpu/drm/ttm/ttm_bo.c:256
Code: 02 00 0f 85 51 01 00 00 48 8b 7b 08 e8 d2 20 01 00 e9 80 fd ff ff e8 d8 15 c0 fe 90 0f 0b 90 e9 e1 f8 ff ff e8 ca 15 c0 fe 90 <0f> 0b 90 e9 a4 f8 ff ff e8 bc 15 c0 fe be 03 00 00 00 4c 89 e7 e8
msg: 00000000: 05 00 d0 c1 04 00 f0 f1 01 30 00 00 2d 90 00 00 .........0..-...
RSP: 0018:ffffc9000f5cf710 EFLAGS: 00010293
RAX: 0000000000000000 RBX: ffff888018e5d2a8 RCX: ffffffff82bb1b36
RDX: ffff888017b68000 RSI: 0000000000000004 RDI: ffff888018e5d2a8
msg: 00000010: 19 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
RBP: ffff88801261c720 R08: 0000000000000001 R09: ffffed10031cba55
R10: ffff888018e5d2ab R11: 00000000000000f3 R12: ffff888018e5d290
R13: ffff888018e5d2d4 R14: ffff88801b219c18 R15: dffffc0000000000
FS: 0000000000000000(0000) GS:ffff8880e0f6f000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31223ffc CR3: 0000000028e00005 CR4: 0000000000770ef0
PKRU: 80000000
Call Trace:
<TASK>
kref_put include/linux/kref.h:65 [inline]
ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:325 [inline]
ttm_bo_fini+0x55/0x80 drivers/gpu/drm/ttm/ttm_bo.c:330
nouveau_gem_object_del+0xb2/0x1b0 drivers/gpu/drm/nouveau/nouveau_gem.c:90
drm_gem_object_free+0x5f/0x90 drivers/gpu/drm/drm_gem.c:1165
kref_put include/linux/kref.h:65 [inline]
__drm_gem_object_put include/drm/drm_gem.h:562 [inline]
drm_gem_object_put include/drm/drm_gem.h:575 [inline]
nouveau_abi16_chan_fini.constprop.0+0x44f/0x5a0 drivers/gpu/drm/nouveau/nouveau_abi16.c:195
nouveau 0000:01:00.0: syz.2.23[2209]: Unknown handle 0x00000000
nouveau_abi16_fini+0x1d0/0x340 drivers/gpu/drm/nouveau/nouveau_abi16.c:225
nouveau_drm_postclose+0x18b/0x3e0 drivers/gpu/drm/nouveau/nouveau_drm.c:1284
nouveau 0000:01:00.0: syz.2.23[2209]: validate_init
drm_file_free.part.0+0x6d6/0xb60 drivers/gpu/drm/drm_file.c:267
drm_file_free drivers/gpu/drm/drm_file.c:237 [inline]
drm_close_helper.isra.0+0x11a/0x160 drivers/gpu/drm/drm_file.c:290
drm_release+0x1ab/0x330 drivers/gpu/drm/drm_file.c:438
__fput+0x39c/0xa60 fs/file_table.c:512
nouveau 0000:01:00.0: syz.2.23[2209]: validate: -2
task_work_run+0x15a/0x230 kernel/task_work.c:233
exit_task_work include/linux/task_work.h:40 [inline]
do_exit+0x82b/0x25a0 kernel/exit.c:1009
do_group_exit+0xc2/0x280 kernel/exit.c:1152
get_signal+0x1d6e/0x1f30 kernel/signal.c:3046
arch_do_signal_or_restart+0x7d/0x6e0 arch/x86/kernel/signal.c:337
__exit_to_user_mode_loop kernel/entry/common.c:66 [inline]
exit_to_user_mode_loop+0xdf/0x440 kernel/entry/common.c:101
__exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline]
syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline]
syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline]
do_syscall_64+0x4f8/0x690 arch/x86/entry/syscall_64.c:100
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RI
---truncated---
Published: 2026-10-18
Score: n/a
EPSS: n/a
KEV: No
Impact: Kernel warning due to incorrect pin count; could lead to driver instability.
Action: Apply Patch
AI Analysis

Impact

A function responsible for re‑pinning buffer objects in the Nouveau driver increments the internal pin count even when the pinning request fails due to domain incompatibility. The caller interprets this as a successful pin and never decrements the count, resulting in an inaccurate pin counter. This state inconsistency triggers a WARN_ON_ONCE in ttm_bo_release, signalling that the driver’s internal state is corrupt but no confirmed crash or exploit has been documented.

Affected Systems

All installations of the Linux kernel that ship the Nouveau DRM driver are affected, regardless of distribution. No specific kernel versions are listed in the advisory, so the issue applies to all releases prior to the fix committed to the repository.

Risk and Exploitability

The advisory does not provide a CVSS score, and the EPSS score is not available. The vulnerability is local; an attacker must interact with the Nouveau driver, which typically requires privileged access. The bug causes a WARN_ON_ONCE in ttm_bo_release due to an incorrect pin count, indicating internal state inconsistency. Although such a warning may accompany an eventual kernel panic if the issue is repeated, no confirmed evidence of a crash or exploitation has been reported. The CISA KEV database does not list this vulnerability, suggesting that publicly documented exploitation is not yet known.

Generated by OpenCVE AI on October 18, 2026 at 23:37 UTC.

Remediation

No solution or workaround provided in the CVE record.

OpenCVE Recommended Actions

  • Update the Linux kernel to a version that contains the Nouveau driver fix (the change is referenced by multiple Git commits in the advisory).
  • If an immediate kernel upgrade is not possible, consider disabling the Nouveau driver temporarily by adding "blacklist nouveau" or passing the kernel parameter "nouveau.modeset=0" so that the system does not load the vulnerable module.
  • Continuously monitor kernel logs (e.g., /var/log/kern.log) for WARN_ON_ONCE messages related to ttm_bo_release, and investigate any occurrences promptly.

Generated by OpenCVE AI on October 18, 2026 at 23:37 UTC.

Tracking

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Advisories

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History

Mon, 19 Oct 2026 00:00:00 +0000

Type Values Removed Values Added
Weaknesses CWE-665

Sun, 18 Oct 2026 15:30:00 +0000

Type Values Removed Values Added
Description In the Linux kernel, the following vulnerability has been resolved: drm/nouveau: don't bump pin count on failed re-pin in nouveau_bo_pin_locked() nouveau_bo_pin_locked() checks whether an already pinned BO is in a memory domain compatible with a new pin request. When the domains are incompatible, it sets -EBUSY but still calls ttm_bo_pin() before returning. Callers treat a failed nouveau_bo_pin() as not having acquired a new pin, so the extra pin count is never decreased by a matching unpin. This triggers the warning in ttm_bo_release(): WARN_ON_ONCE(bo->pin_count); Found when fuzzing the nouveau driver with a modified Syzkaller: WARNING: drivers/gpu/drm/ttm/ttm_bo.c:256 at ttm_bo_release+0x827/0x9e0 drivers/gpu/drm/ttm/ttm_bo.c:256, CPU#1: syz.3.24/2212 Modules linked in: CPU: 1 UID: 0 PID: 2212 Comm: syz.3.24 Not tainted 7.2.0 #24 PREEMPT(lazy) nouveau 0000:01:00.0: gsp:msg fn:103 len:0x40/0x20 res:0x19 resp:0x19 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014 RIP: 0010:ttm_bo_release+0x827/0x9e0 drivers/gpu/drm/ttm/ttm_bo.c:256 Code: 02 00 0f 85 51 01 00 00 48 8b 7b 08 e8 d2 20 01 00 e9 80 fd ff ff e8 d8 15 c0 fe 90 0f 0b 90 e9 e1 f8 ff ff e8 ca 15 c0 fe 90 <0f> 0b 90 e9 a4 f8 ff ff e8 bc 15 c0 fe be 03 00 00 00 4c 89 e7 e8 msg: 00000000: 05 00 d0 c1 04 00 f0 f1 01 30 00 00 2d 90 00 00 .........0..-... RSP: 0018:ffffc9000f5cf710 EFLAGS: 00010293 RAX: 0000000000000000 RBX: ffff888018e5d2a8 RCX: ffffffff82bb1b36 RDX: ffff888017b68000 RSI: 0000000000000004 RDI: ffff888018e5d2a8 msg: 00000010: 19 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ RBP: ffff88801261c720 R08: 0000000000000001 R09: ffffed10031cba55 R10: ffff888018e5d2ab R11: 00000000000000f3 R12: ffff888018e5d290 R13: ffff888018e5d2d4 R14: ffff88801b219c18 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff8880e0f6f000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000001b31223ffc CR3: 0000000028e00005 CR4: 0000000000770ef0 PKRU: 80000000 Call Trace: <TASK> kref_put include/linux/kref.h:65 [inline] ttm_bo_put drivers/gpu/drm/ttm/ttm_bo.c:325 [inline] ttm_bo_fini+0x55/0x80 drivers/gpu/drm/ttm/ttm_bo.c:330 nouveau_gem_object_del+0xb2/0x1b0 drivers/gpu/drm/nouveau/nouveau_gem.c:90 drm_gem_object_free+0x5f/0x90 drivers/gpu/drm/drm_gem.c:1165 kref_put include/linux/kref.h:65 [inline] __drm_gem_object_put include/drm/drm_gem.h:562 [inline] drm_gem_object_put include/drm/drm_gem.h:575 [inline] nouveau_abi16_chan_fini.constprop.0+0x44f/0x5a0 drivers/gpu/drm/nouveau/nouveau_abi16.c:195 nouveau 0000:01:00.0: syz.2.23[2209]: Unknown handle 0x00000000 nouveau_abi16_fini+0x1d0/0x340 drivers/gpu/drm/nouveau/nouveau_abi16.c:225 nouveau_drm_postclose+0x18b/0x3e0 drivers/gpu/drm/nouveau/nouveau_drm.c:1284 nouveau 0000:01:00.0: syz.2.23[2209]: validate_init drm_file_free.part.0+0x6d6/0xb60 drivers/gpu/drm/drm_file.c:267 drm_file_free drivers/gpu/drm/drm_file.c:237 [inline] drm_close_helper.isra.0+0x11a/0x160 drivers/gpu/drm/drm_file.c:290 drm_release+0x1ab/0x330 drivers/gpu/drm/drm_file.c:438 __fput+0x39c/0xa60 fs/file_table.c:512 nouveau 0000:01:00.0: syz.2.23[2209]: validate: -2 task_work_run+0x15a/0x230 kernel/task_work.c:233 exit_task_work include/linux/task_work.h:40 [inline] do_exit+0x82b/0x25a0 kernel/exit.c:1009 do_group_exit+0xc2/0x280 kernel/exit.c:1152 get_signal+0x1d6e/0x1f30 kernel/signal.c:3046 arch_do_signal_or_restart+0x7d/0x6e0 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0xdf/0x440 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x4f8/0x690 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f RI ---truncated---
Title drm/nouveau: don't bump pin count on failed re-pin in nouveau_bo_pin_locked()
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Subscriptions

Linux Linux Kernel
cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-10-18T15:17:25.033Z

Reserved: 2026-09-25T10:25:14.354Z

Link: CVE-2026-98511

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-18T16:17:02.310

Modified: 2026-10-18T16:17:02.310

Link: CVE-2026-98511

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-19T02:45:15Z

Weaknesses