CVE-2026-98142drm/cirrus-qemu: Validate BAR0 size during probe

In the Linux kernel, the following vulnerability has been resolved: drm/cirrus-qemu: Validate BAR0 size during probe The `cirrus-qemu` driver relies on `CIRRUS_VRAM_SIZE` (4 MB) to validate framebuffer sizes. However, during PCI probe, the driver mapped BAR0 without verifying that its size matches `CIRRUS_VRAM_SIZE`. If a PCI device with a BAR0 smaller than 4 MB is bound to the driver, the mapped VRAM will be smaller than expected. Because validation checks assume 4 MB VRAM, framebuffers larger than the mapped memory can be created. When the display plane is updated (e.g. during release), `cirrus_primary_plane_helper_atomic_update()` copies the framebuffer to VRAM using `drm_fb_memcpy()`. Writing past the end of the mapped I/O memory causes a supervisor write page fault: BUG: unable to handle page fault for address: ffffc9000389c000 ... RIP: 0010:memcpy_toio+0x7c/0xe0 arch/x86/lib/iomem.c:110 ... Call Trace: <TASK> iosys_map_memcpy_to include/linux/iosys-map.h:285 [inline] drm_fb_memcpy+0x325/0x5d0 drivers/gpu/drm/drm_format_helper.c:442 cirrus_primary_plane_helper_atomic_update+0x98a/0xb00 drivers/gpu/drm/tiny/cirrus-qemu.c:358 drm_atomic_helper_commit_planes+0x626/0xea0 drivers/gpu/drm/drm_atomic_helper.c:3038 drm_atomic_helper_commit_tail+0x60/0x510 drivers/gpu/drm/drm_atomic_helper.c:1989 commit_tail+0x2b1/0x3c0 drivers/gpu/drm/drm_atomic_helper.c:2074 drm_atomic_helper_commit+0xa77/0xb10 drivers/gpu/drm/drm_atomic_helper.c:2312 Fix this by validating in `cirrus_pci_probe()` that the PCI BAR0 resource is not less than `CIRRUS_VRAM_SIZE`, returning `-ENODEV` if it is less.

CVSS

Not yet scored

Weakness (CWE)

Not given

Known exploited

Not in CISA's KEV catalog

EPSS (exploitation in the next 30 days)

Not loaded for this CVE

Assigned by

Linux

NVD analysis

Undergoing Analysis

Record last updated

Oct 3, 2026

First seen by InfoSec Signals

Oct 9, 2026

The CVE record on cve.org · NVD's entry

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