drm/cirrus-qemu: Validate BAR0 size during probe
Summary
| CVE | CVE-2026-98142 |
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| State | PUBLISHED |
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| Assigner | Linux |
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| Source Priority | CVE Program / NVD first with legacy fallback |
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| Published | 2026-09-25 11:17:45 UTC |
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| Updated | 2026-09-25 11:17:45 UTC |
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| Description | 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. |
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Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|
| CNA |
Linux |
Linux |
affected ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 0b5084a1f070ad1fc34e11945644ae034bbc774c git |
Not specified |
| CNA |
Linux |
Linux |
affected ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 26bd90c886218f36c9adeab206b0e27b4384e2f6 git |
Not specified |
| CNA |
Linux |
Linux |
affected ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 144f51cd0ccc3ad47a6099917b7bb535611fb18f git |
Not specified |
| CNA |
Linux |
Linux |
affected ab3e023b1b4c9887c9f0f761b47f3f0516bd3434 92312d333bf700798f92f30406c721bce87506f3 git |
Not specified |
| CNA |
Linux |
Linux |
affected 5.2 |
Not specified |
| CNA |
Linux |
Linux |
unaffected 5.2 semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.12.111 6.12.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 6.18.53 6.18.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.2.7 7.2.* semver |
Not specified |
| CNA |
Linux |
Linux |
unaffected 7.3-rc2 * original_commit_for_fix |
Not specified |
References
| Reference | Source | Link | Tags |
|---|
| git.kernel.org/stable/c/144f51cd0ccc3ad47a6099917b7bb535611fb18f |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/26bd90c886218f36c9adeab206b0e27b4384e2f6 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/92312d333bf700798f92f30406c721bce87506f3 |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| git.kernel.org/stable/c/0b5084a1f070ad1fc34e11945644ae034bbc774c |
416baaa9-dc9f-4396-8d5f-8c081fb06d67 |
git.kernel.org |
|
| CVE Program record |
CVE.ORG |
www.cve.org |
canonical |
| NVD vulnerability detail |
NVD |
nvd.nist.gov |
canonical, analysis |
No vendor comments have been submitted for this CVE.
There are currently no legacy QID mappings associated with this CVE.