On 11/15/24 13:36, Lorenzo Stoakes wrote:
> Critical fixes for mmap_region(), backported to 5.10.y.
>
> Some notes on differences from upstream:
>
> * We do NOT take commit 0fb4a7ad270b ("mm: refactor
> map_deny_write_exec()"), as this refactors code only introduced in 6.2.
>
> * We make reference in "mm: refactor arch_calc_vm_flag_bits() and arm64 MTE
> handling" to parisc, but the referenced functionality does not exist in
> this kernel.
>
> * In this kernel is_shared_maywrite() does not exist and the code uses
> VM_SHARED to determine whether mapping_map_writable() /
> mapping_unmap_writable() should be invoked. This backport therefore
> follows suit.
>
> * The vma_dummy_vm_ops static global doesn't exist in this kernel, so we
> use a local static variable in mmap_file() and vma_close().
>
> * Each version of these series is confronted by a slightly different
> mmap_region(), so we must adapt the change for each stable version. The
> approach remains the same throughout, however, and we correctly avoid
> closing the VMA part way through any __mmap_region() operation.
>
> * In 5.10 we must handle VM_DENYWRITE. Since this is done at the top of the
> file-backed VMA handling logic, and importantly before mmap_file() invocation,
> this does not imply any additional difficult error handling on partial
> completion of mapping so has no significant impact.
Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>
> Lorenzo Stoakes (4):
> mm: avoid unsafe VMA hook invocation when error arises on mmap hook
> mm: unconditionally close VMAs on error
> mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling
> mm: resolve faulty mmap_region() error path behaviour
>
> arch/arm64/include/asm/mman.h | 10 +++--
> include/linux/mman.h | 7 +--
> mm/internal.h | 19 ++++++++
> mm/mmap.c | 82 +++++++++++++++++++++--------------
> mm/nommu.c | 9 ++--
> mm/shmem.c | 3 --
> mm/util.c | 33 ++++++++++++++
> 7 files changed, 117 insertions(+), 46 deletions(-)
>
> --
> 2.47.0
