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When declaring an immutable global variable in Rust, the compiler checks
that it looks thread safe, because it is generally safe to access said
global variable. When using C bindings types for these globals, we don't
really want this check, because it is conservative and assumes pointers
are not thread safe.
In the case of BINDER_VM_OPS, this is a challenge when combined with the
patch 'userfaultfd: introduce vm_uffd_ops' [1], which introduces a
pointer field to vm_operations_struct. It previously only held function
pointers, which are considered thread safe.
Rust Binder should not be assuming that vm_operations_struct contains no
pointer fields, so to fix this, use AssertSync (which Rust Binder has
already declared for another similar global of type struct
file_operations with the same problem). This ensures that even if
another commit adds a pointer field to vm_operations_struct, this does
not cause problems.
Fixes: 8ef2c15aea ("rust_binder: check ownership before using vma")
Cc: stable <stable@kernel.org>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202603121235.tpnRxFKO-lkp@intel.com/
Link: https://lore.kernel.org/r/20260306171815.3160826-8-rppt@kernel.org [1]
Signed-off-by: Alice Ryhl <aliceryhl@google.com>
Reviewed-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260314111951.4139029-1-aliceryhl@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>