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commit6c21e066f9upstream. mbind() calls down into vma_replace_policy() without taking the per-VMA locks, replaces the VMA's vma->vm_policy pointer, and frees the old policy. That's bad; a concurrent page fault might still be using the old policy (in vma_alloc_folio()), resulting in use-after-free. Normally this will manifest as a use-after-free read first, but it can result in memory corruption, including because vma_alloc_folio() can call mpol_cond_put() on the freed policy, which conditionally changes the policy's refcount member. This bug is specific to CONFIG_NUMA, but it does also affect non-NUMA systems as long as the kernel was built with CONFIG_NUMA. Signed-off-by: Jann Horn <jannh@google.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Fixes:5e31275cc9("mm: add per-VMA lock and helper functions to control it") Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
3173 lines
79 KiB
3173 lines
79 KiB