Description (CNA)
In the Linux kernel, the following vulnerability has been resolved: mm/khugepaged: fix ->anon_vma race If an ->anon_vma is attached to the VMA, collapse_and_free_pmd() requires it to be locked. Page table traversal is allowed under any one of the mmap lock, the anon_vma lock (if the VMA is associated with an anon_vma), and the mapping lock (if the VMA is associated with a mapping); and so to be able to remove page tables, we must hold all three of them. retract_page_tables() bails out if an ->anon_vma is attached, but does this check before holding the mmap lock (as the comment above the check explains). If we racily merged an existing ->anon_vma (shared with a child process) from a neighboring VMA, subsequent rmap traversals on pages belonging to the child will be able to see the page tables that we are concurrently removing while assuming that nothing else can access them. Repeat the ->anon_vma check once we hold the mmap lock to ensure that there really is no concurrent page table access. Hitting this bug causes a lockdep warning in collapse_and_free_pmd(), in the line "lockdep_assert_held_write(&vma->anon_vma->root->rwsem)". It can also lead to use-after-free access.
Affected (CNA)
| Vendor / product | Versions |
|---|---|
| Linux / Linux | affected f3f0e1d2150b2b99da2cbdfaad000089efe9bf30 before 352fbf61ce776fef18dca6a68680a6cd943dac95; affected f3f0e1d2150b2b99da2cbdfaad000089efe9bf30 before cee956ab1efbd858b4ca61c8b474af5aa24b29a6; affected f3f0e1d2150b2b99da2cbdfaad000089efe9bf30 before abdf3c33918185c3e8ffeb09ed3e334b3d7df47c; affected f3f0e1d2150b2b99da2cbdfaad000089efe9bf30 before acb08187b5a83cdb9ac4112fae9e18cf983b0128; affected f3f0e1d2150b2b99da2cbdfaad000089efe9bf30 before 023f47a8250c6bdb4aebe744db4bf7f73414028b |
| Linux / Linux | affected 4.8; unaffected 0 before 4.8; unaffected 5.4.299 through 5.4.*; unaffected 5.10.243 through 5.10.*; unaffected 5.15.192 through 5.15.*; unaffected 6.1.11 through 6.1.*; unaffected 6.2 through * |
CWE
No CWE identifiers supplied.
References
- https://git.kernel.org/stable/c/352fbf61ce776fef18dca6a68680a6cd943dac95
- https://git.kernel.org/stable/c/cee956ab1efbd858b4ca61c8b474af5aa24b29a6
- https://git.kernel.org/stable/c/abdf3c33918185c3e8ffeb09ed3e334b3d7df47c
- https://git.kernel.org/stable/c/acb08187b5a83cdb9ac4112fae9e18cf983b0128
- https://git.kernel.org/stable/c/023f47a8250c6bdb4aebe744db4bf7f73414028b
ADP enrichment
No English description supplied.
No references supplied.
No English description supplied.