virt: sev-guest: Do not use host-controlled page order in cleanup path
When issuing an extended guest request (SVM_VMGEXIT_EXT_GUEST_REQUEST),
get_ext_report() allocates a buffer to retrieve a certificate blob from the
host, keeping track of its size in report_req->certs_len.
However, the host may return SNP_GUEST_VMM_ERR_INVALID_LEN, indicating
an invalid buffer size, as well as the expected length of such buffer.
get_ext_report() subsequently updates report_req->certs_len with the
host-controlled value, and cleans up the buffer by computing a page order
from such value. This is incorrect, as the host-provided length may not
match the page order of the original allocation, potentially resulting
in corruption in the page allocator.
Fix this by using alloc_pages_exact() instead, and reusing @npages to
compute the size passed to free_pages_exact(). For consistency, also
use @npages to compute the size when allocating the pages, even though
this last change has no functional effect.
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Linux | Linux | unaffected |
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| Linux | Linux | affected |
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Solution
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Workaround
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Wed, 24 Jun 2026 19:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Weaknesses | CWE-239 CWE-787 |
Wed, 24 Jun 2026 17:15:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Description | In the Linux kernel, the following vulnerability has been resolved: virt: sev-guest: Do not use host-controlled page order in cleanup path When issuing an extended guest request (SVM_VMGEXIT_EXT_GUEST_REQUEST), get_ext_report() allocates a buffer to retrieve a certificate blob from the host, keeping track of its size in report_req->certs_len. However, the host may return SNP_GUEST_VMM_ERR_INVALID_LEN, indicating an invalid buffer size, as well as the expected length of such buffer. get_ext_report() subsequently updates report_req->certs_len with the host-controlled value, and cleans up the buffer by computing a page order from such value. This is incorrect, as the host-provided length may not match the page order of the original allocation, potentially resulting in corruption in the page allocator. Fix this by using alloc_pages_exact() instead, and reusing @npages to compute the size passed to free_pages_exact(). For consistency, also use @npages to compute the size when allocating the pages, even though this last change has no functional effect. | |
| Title | virt: sev-guest: Do not use host-controlled page order in cleanup path | |
| First Time appeared |
Linux
Linux linux Kernel |
|
| CPEs | cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* | |
| Vendors & Products |
Linux
Linux linux Kernel |
|
| References |
|
Projects
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MITRE
Status: PUBLISHED
Assigner: Linux
Published:
Updated: 2026-06-24T16:28:40.391Z
Reserved: 2026-06-09T07:44:35.373Z
Link: CVE-2026-52959
Vulnrichment
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NVD
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Redhat
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OpenCVE Enrichment
Updated: 2026-06-24T19:15:15Z