Linux Kernel: amdxdna_insert_pages VMA close() misuse causes refunderflow
CVE-2026-74721 Published on August 22, 2026
accel/amxdna: Fix page-insertion errors in amdxdna_insert_pages()
In the Linux kernel, the following vulnerability has been resolved:
accel/amxdna: Fix page-insertion errors in amdxdna_insert_pages()
Two error paths in amdxdna_insert_pages() called vma->vm_ops->close(vma)
before returning an error code to the caller. This is incorrect:
amdxdna_gem_obj_mmap() registers an HMM interval notifier before calling
amdxdna_insert_pages(), and on a hard error it jumps to hmm_unreg to undo
that registration. Calling vm_ops->close() manually which drops the
shmem pages_pin_count and the GEM object reference that backs the VMA
before the mmap syscall has even returned causes those resources to be
released while the VMA is still alive. The kernel VMA teardown will call
vm_ops->close() a second time when the process later unmaps the range,
producing a reference count underflow.
Replace both hard-error returns with a deferred-fault approach that keeps
the VMA alive and retries page insertion through the HMM range-fault path.
Products Associated with CVE-2026-74721
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Affected Versions
Linux:- Version e486147c912f653ef4b60a6c7dbd4168a4c56a9f and below 1501e4d07c6fee0d50531a0d1cb2be01a63e6e75 is affected.
- Version e486147c912f653ef4b60a6c7dbd4168a4c56a9f and below 8d51e0fd3e698919d2adeff71936377f0c0d4aa0 is affected.
- Version 6.16 is affected.
- Before 6.16 is unaffected.
- Version 7.1.9, <= 7.1.* is unaffected.
- Version 7.2, <= * is unaffected.