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.
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