Linux Kernel PCI P2PDMA mmap Refcount Warning Fix
CVE-2026-46268 Published on June 3, 2026
PCI/P2PDMA: Fix p2pmem_alloc_mmap() warning condition
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.
Products Associated with CVE-2026-46268
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Affected Versions
Linux:- Version b7e2823787735ca009e63f35f164b46df0ef096c and below eb9aa9f8010465d927864f5a35bdc5604b0ff51a is affected.
- Version b7e2823787735ca009e63f35f164b46df0ef096c and below 9b69243983fb2f4d4d1f4ef0989bc1296547dc2c is affected.
- Version b7e2823787735ca009e63f35f164b46df0ef096c and below cb500023a75246f60b79af9f7321d6e75330c5b5 is affected.
- Version 6.15 is affected.
- Before 6.15 is unaffected.
- Version 6.18.14, <= 6.18.* is unaffected.
- Version 6.19.4, <= 6.19.* is unaffected.
- Version 7.0, <= * is unaffected.