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Vulnerability CVE-2024-47674
Published: 2024-10-15
| Description: |
In the Linux kernel, the following vulnerability has been resolved:
mm: avoid leaving partial pfn mappings around in error case
As Jann points out, PFN mappings are special, because unlike normal
memory mappings, there is no lifetime information associated with the
mapping - it is just a raw mapping of PFNs with no reference counting of
a 'struct page'.
That's all very much intentional, but it does mean that it's easy to
mess up the cleanup in case of errors. Yes, a failed mmap() will always
eventually clean up any partial mappings, but without any explicit
lifetime in the page table mapping itself, it's very easy to do the
error handling in the wrong order.
In particular, it's easy to mistakenly free the physical backing store
before the page tables are actually cleaned up and (temporarily) have
stale dangling PTE entries.
To make this situation less error-prone, just make sure that any partial
pfn mapping is torn down early, before any other error handling. |
References: |
https://git.kernel.org/stable/c/65d0db500d7c07f0f76fc24a4d837791c4862cd2
https://git.kernel.org/stable/c/a95a24fcaee1b892e47d5e6dcc403f713874ee80
https://git.kernel.org/stable/c/954fd4c81f22c4b6ba65379a81fd252971bf4ef3
https://git.kernel.org/stable/c/79a61cc3fc0466ad2b7b89618a6157785f0293b3
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