mm: shrinker: fix NULL pointer dereference in debugfs
Summary
| CVE | CVE-2026-64417 |
|---|---|
| State | PUBLISHED |
| Assigner | Linux |
| Source Priority | CVE Program / NVD first with legacy fallback |
| Published | 2026-07-25 10:17:25 UTC |
| Updated | 2026-07-25 10:17:25 UTC |
| Description | In the Linux kernel, the following vulnerability has been resolved: mm: shrinker: fix NULL pointer dereference in debugfs shrinker_debugfs_add() creates both "count" and "scan" debugfs files unconditionally. That assumes every shrinker implements both count_objects() and scan_objects(), which is not guaranteed. For example, the xen-backend shrinker sets count_objects() but leaves scan_objects() NULL, so writing to its scan file calls through a NULL function pointer and panics the kernel: BUG: kernel NULL pointer dereference, address: 0000000000000000 RIP: 0010:0x0 Code: Unable to access opcode bytes at 0xffffffffffffffd6. Call Trace: <TASK> shrinker_debugfs_scan_write+0x12e/0x270 full_proxy_write+0x5f/0x90 vfs_write+0xde/0x420 ? filp_flush+0x75/0x90 ? filp_close+0x1d/0x30 ? do_dup2+0xb8/0x120 ksys_write+0x68/0xf0 ? filp_flush+0x75/0x90 do_syscall_64+0xb3/0x5b0 entry_SYSCALL_64_after_hwframe+0x76/0x7e The count path has the same issue in principle if a shrinker omits count_objects(). To fix it, only create "count" and "scan" debugfs files when the corresponding callbacks are present. |
Risk And Classification
EPSS: 0.001730000 probability, percentile 0.069630000 (date 2026-07-28)
Vendor Declared Affected Products
| Source | Vendor | Product | Version | Platforms |
|---|---|---|---|---|
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 ebb45c2648b1f60715fd283700f651e05e431231 git | Not specified |
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9 git | Not specified |
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 36f8534f461222291a74156ab91f3ba9f09b6f93 git | Not specified |
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 006467ab932698612398f853344a7405164541f4 git | Not specified |
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 b9beed2322f3538b0d2d53307062da4102b8d8d8 git | Not specified |
| CNA | Linux | Linux | affected bbf535fd6f06b94b9d07ed6f09397a936d4a58d8 e30453c61e185e914fde83c650e268067b140218 git | Not specified |
| CNA | Linux | Linux | affected 6.0 | Not specified |
| CNA | Linux | Linux | unaffected 6.0 semver | Not specified |
| CNA | Linux | Linux | unaffected 6.1.178 6.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.6.145 6.6.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.12.96 6.12.* semver | Not specified |
| CNA | Linux | Linux | unaffected 6.18.39 6.18.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.1.4 7.1.* semver | Not specified |
| CNA | Linux | Linux | unaffected 7.2-rc3 * original_commit_for_fix | Not specified |
References
| Reference | Source | Link | Tags |
|---|---|---|---|
| git.kernel.org/stable/c/b9beed2322f3538b0d2d53307062da4102b8d8d8 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/ebb45c2648b1f60715fd283700f651e05e431231 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/09d2407985b8ce3e831f9d4310fe7ac06a6b3ae9 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/006467ab932698612398f853344a7405164541f4 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/36f8534f461222291a74156ab91f3ba9f09b6f93 | 416baaa9-dc9f-4396-8d5f-8c081fb06d67 | git.kernel.org | |
| git.kernel.org/stable/c/e30453c61e185e914fde83c650e268067b140218 | 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.