CVE-2026-46268: PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition

Severity: medium (CVSS 5.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.1% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-06-03 · updated 2026-07-22

Description

In the Linux kernel, the following vulnerability has been resolved: PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition Commit b7e282378773 has already changed the initial page refcount of p2pdma page from one to zero, however, in p2pmem_alloc_mmap() it uses "VM_WARN_ON_ONCE_PAGE(!page_ref_count(page))" to assert the initial page refcount should not be zero and the following will be reported when CONFIG_DEBUG_VM is enabled: page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x380400000 flags: 0x20000000002000(reserved|node=0|zone=4) raw: 0020000000002000 ff1100015e3ab440 0000000000000000 0000000000000000 raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000 page dumped because: VM_WARN_ON_ONCE_PAGE(!page_ref_count(page)) ------------[ cut here ]------------ WARNING: CPU: 5 PID: 449 at drivers/pci/p2pdma.c:240 p2pmem_alloc_mmap+0x83a/0xa60 Fix by using "page_ref_count(page)" as the assertion condition.

Affected products

Linux kernel: from 6.15 before 6.18.14; from 6.19 before 6.19.4 — fixed in 6.18.14, 6.19.4

How to fix

Upgrade to a fixed version: Linux kernel 6.18.14, 6.19.4. Check the vendor advisory for mitigations.

References

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