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6ccdc91d6a
linux/mm
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Linus Torvalds 6014bc2756 x86-64: make access_ok() independent of LAM 
The linear address masking (LAM) code made access_ok() more complicated,
in that it now needs to untag the address in order to verify the access
range.  See commit 74c228d20a ("x86/uaccess: Provide untagged_addr()
and remove tags before address check").

We were able to avoid that overhead in the get_user/put_user code paths
by simply using the sign bit for the address check, and depending on the
GP fault if the address was non-canonical, which made it all independent
of LAM.

And we can do the same thing for access_ok(): simply check that the user
pointer range has the high bit clear.  No need to bother with any
address bit masking.

In fact, we can go a bit further, and just check the starting address
for known small accesses ranges: any accesses that overflow will still
be in the non-canonical area and will still GP fault.

To still make syzkaller catch any potentially unchecked user addresses,
we'll continue to warn about GP faults that are caused by accesses in
the non-canonical range.  But we'll limit that to purely "high bit set
and past the one-page 'slop' area".

We could probably just do that "check only starting address" for any
arbitrary range size: realistically all kernel accesses to user space
will be done starting at the low address.  But let's leave that kind of
optimization for later.  As it is, this already allows us to generate
simpler code and not worry about any tag bits in the address.

The one thing to look out for is the GUP address check: instead of
actually copying data in the virtual address range (and thus bad
addresses being caught by the GP fault), GUP will look up the page
tables manually.  As a result, the page table limits need to be checked,
and that was previously implicitly done by the access_ok().

With the relaxed access_ok() check, we need to just do an explicit check
for TASK_SIZE_MAX in the GUP code instead.  The GUP code already needs
to do the tag bit unmasking anyway, so there this is all very
straightforward, and there are no LAM issues.

Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2023-05-03 10:37:22 -07:00
..
damon mm/damon/sysfs: make more kobj_type structures constant 2023-04-05 19:42:59 -07:00
kasan kasan: fix lockdep report invalid wait context 2023-04-21 14:51:59 -07:00
kfence - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
kmsan printk: export console trace point for kcsan/kasan/kfence/kmsan 2023-04-18 16:30:11 -07:00
backing-dev.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
balloon_compaction.c mm: Convert all PageMovable users to movable_operations 2022-08-02 12:34:03 -04:00
bootmem_info.c bootmem: remove the vmemmap pages from kmemleak in put_page_bootmem 2022-08-28 14:02:45 -07:00
cma_debug.c mm/cma_debug: show complete cma name in debugfs directories 2022-09-11 20:25:50 -07:00
cma_sysfs.c mm: cma: make kobj_type structure constant 2023-03-28 16:20:06 -07:00
cma.c mm: move most of core MM initialization to mm/mm_init.c 2023-04-05 19:42:52 -07:00
cma.h mm/cma: provide option to opt out from exposing pages on activation failure 2022-03-22 15:57:09 -07:00
compaction.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
debug_page_ref.c
debug_vm_pgtable.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
debug.c mm/debug: use %pGt to display page_type in dump_page() 2023-03-28 16:20:09 -07:00
dmapool_test.c dmapool: add alloc/free performance test 2023-04-05 19:42:38 -07:00
dmapool.c dmapool: create/destroy cleanup 2023-04-05 19:42:41 -07:00
early_ioremap.c mm/early_ioremap: declare early_memremap_pgprot_adjust() 2022-03-22 15:57:11 -07:00
fadvise.c mm: support POSIX_FADV_NOREUSE 2023-01-18 17:12:57 -08:00
failslab.c mm: fix unexpected changes to {failslab|fail_page_alloc}.attr 2022-11-22 18:50:44 -08:00
filemap.c mm: return an ERR_PTR from __filemap_get_folio 2023-04-05 19:42:42 -07:00
folio-compat.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
frontswap.c frontswap: don't call ->init if no ops are registered 2022-09-26 12:14:34 -07:00
gup_test.c mm/gup_test: free memory allocated via kvcalloc() using kvfree() 2022-12-15 16:37:48 -08:00
gup_test.h mm/gup_test: start/stop/read functionality for PIN LONGTERM test 2022-11-08 17:37:15 -08:00
gup.c x86-64: make access_ok() independent of LAM 2023-05-03 10:37:22 -07:00
highmem.c highmem: fix kmap_to_page() for kmap_local_page() addresses 2022-10-12 18:51:51 -07:00
hmm.c mm/hugetlb: make walk_hugetlb_range() safe to pmd unshare 2023-01-18 17:12:39 -08:00
huge_memory.c mm: don't check VMA write permissions if the PTE/PMD indicates write permissions 2023-04-21 14:52:03 -07:00
hugetlb_cgroup.c mm/hugetlb: increase use of folios in alloc_huge_page() 2023-02-13 15:54:27 -08:00
hugetlb_vmemmap.c mm, page_alloc: use check_pages_enabled static key to check tail pages 2023-04-18 16:29:54 -07:00
hugetlb_vmemmap.h mm: hugetlb_vmemmap: improve hugetlb_vmemmap code readability 2022-08-08 18:06:43 -07:00
hugetlb.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
hwpoison-inject.c mm/hwpoison: add __init/__exit annotations to module init/exit funcs 2022-10-03 14:03:05 -07:00
init-mm.c IOMMU Updates for Linux 6.4 2023-04-30 13:00:38 -07:00
internal.h mm: correct arg in reclaim_pages()/reclaim_clean_pages_from_list() 2023-04-21 14:52:02 -07:00
interval_tree.c
io-mapping.c
ioremap.c mm: ioremap: Add ioremap/iounmap_allowed() 2022-06-27 12:22:31 +01:00
Kconfig - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
Kconfig.debug - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
khugepaged.c mm/khugepaged: fix conflicting mods to collapse_file() 2023-04-27 13:42:16 -07:00
kmemleak.c lib/stackdepot, mm: rename stack_depot_want_early_init 2023-02-16 20:43:49 -08:00
ksm.c mm: add new KSM process and sysfs knobs 2023-04-21 14:52:03 -07:00
list_lru.c mm: kmem: make mem_cgroup_from_obj() vmalloc()-safe 2022-06-16 19:48:31 -07:00
maccess.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
madvise.c Add support for new Linear Address Masking CPU feature. This is similar 2023-04-28 09:43:49 -07:00
Makefile - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
mapping_dirty_helpers.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
memblock.c mm: avoid passing 0 to __ffs() 2023-04-18 16:29:42 -07:00
memcontrol.c memcg: page_cgroup_ino() get memcg from the page's folio 2023-04-18 16:30:09 -07:00
memfd.c memfd: pass argument of memfd_fcntl as int 2023-04-18 16:30:11 -07:00
memory_hotplug.c mm: avoid passing 0 to __ffs() 2023-04-18 16:29:42 -07:00
memory-failure.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
memory-tiers.c memory tier: release the new_memtier in find_create_memory_tier() 2023-02-09 16:51:40 -08:00
memory.c mm: do not increment pgfault stats when page fault handler retries 2023-04-21 14:52:04 -07:00
mempolicy.c mm/mempolicy: fix use-after-free of VMA iterator 2023-04-16 10:41:25 -07:00
mempool.c mempool: do not use ksize() for poisoning 2022-11-30 15:58:41 -08:00
memremap.c mm/memremap.c: fix outdated comment in devm_memremap_pages 2023-02-09 16:51:46 -08:00
memtest.c mm/memtest: add results of early memtest to /proc/meminfo 2023-04-05 19:42:55 -07:00
migrate_device.c mm: change to return bool for isolate_lru_page() 2023-02-20 12:46:17 -08:00
migrate.c Add support for new Linear Address Masking CPU feature. This is similar 2023-04-28 09:43:49 -07:00
mincore.c mm: return an ERR_PTR from __filemap_get_folio 2023-04-05 19:42:42 -07:00
mlock.c mm: mlock: use folios_put() in mlock_folio_batch() 2023-04-18 16:29:53 -07:00
mm_init.c mm/vmemmap/devdax: fix kernel crash when probing devdax devices 2023-04-18 16:30:09 -07:00
mm_slot.h mm: introduce common struct mm_slot 2022-10-03 14:02:43 -07:00
mmap_lock.c
mmap.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
mmu_gather.c mm: prefer xxx_page() alloc/free functions for order-0 pages 2023-03-28 16:20:16 -07:00
mmu_notifier.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
mmzone.c mm: multi-gen LRU: groundwork 2022-09-26 19:46:09 -07:00
mprotect.c mm/userfaultfd: don't consider uffd-wp bit of writable migration entries 2023-04-18 16:29:53 -07:00
mremap.c mm/mremap: write-lock VMA while remapping it to a new address range 2023-04-05 20:02:58 -07:00
msync.c mm/msync: use vma_find() instead of vma linked list 2022-09-26 19:46:25 -07:00
nommu.c mm: vmalloc: convert vread() to vread_iter() 2023-04-05 19:42:57 -07:00
oom_kill.c mm/mmu_notifier: remove unused mmu_notifier_range_update_to_read_only export 2023-02-02 22:32:54 -08:00
page_alloc.c cgroup changes for v6.4-rc1 2023-04-29 10:05:22 -07:00
page_counter.c mm: page_counter: remove unneeded atomic ops for low/min 2022-09-11 20:26:01 -07:00
page_ext.c mm/page_ext: init page_ext early if there are no deferred struct pages 2023-02-02 22:33:22 -08:00
page_idle.c mm: page_idle: convert page idle to use a folio 2023-01-18 17:12:52 -08:00
page_io.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
page_isolation.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_owner.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_poison.c
page_reporting.c mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
page_reporting.h
page_table_check.c mm/page_ext: do not allocate space for page_ext->flags if not needed 2023-02-02 22:33:11 -08:00
page_vma_mapped.c mm/hugetlb: introduce hugetlb_walk() 2023-01-18 17:12:39 -08:00
page-writeback.c mm,jfs: move write_one_page/folio_write_one to jfs 2023-03-28 16:20:14 -07:00
pagewalk.c mm/hugetlb: introduce hugetlb_walk() 2023-01-18 17:12:39 -08:00
percpu-internal.h mm: percpu: fix incorrect size in pcpu_obj_full_size() 2023-02-16 20:43:55 -08:00
percpu-km.c
percpu-stats.c mm: use vmalloc_array and vcalloc for array allocations 2022-03-08 09:30:46 -05:00
percpu-vm.c
percpu.c mm: memcontrol: rename memcg_kmem_enabled() 2023-02-16 20:43:56 -08:00
pgalloc-track.h
pgtable-generic.c mm: add PTE pointer parameter to flush_tlb_fix_spurious_fault() 2023-03-28 16:20:12 -07:00
process_vm_access.c use less confusing names for iov_iter direction initializers 2022-11-25 13:01:55 -05:00
ptdump.c mm: pagewalk: Fix race between unmap and page walker 2022-09-03 10:13:13 -07:00
readahead.c readahead: convert readahead_expand() to use a folio 2023-02-02 22:33:21 -08:00
rmap.c mm,unmap: avoid flushing TLB in batch if PTE is inaccessible 2023-04-27 13:42:16 -07:00
rodata_test.c mm/rodata_test: use PAGE_ALIGNED() helper 2022-10-03 14:03:05 -07:00
secretmem.c - Daniel Verkamp has contributed a memfd series ("mm/memfd: add 2023-02-23 17:09:35 -08:00
shmem.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
shrinker_debug.c mm: shrinkers: fix debugfs file permissions 2023-04-21 14:52:03 -07:00
shuffle.c mm/shuffle: convert module_param_call to module_param_cb 2022-10-03 14:03:07 -07:00
shuffle.h mm, treewide: redefine MAX_ORDER sanely 2023-04-05 19:42:46 -07:00
slab_common.c mm/slab: document kfree() as allowed for kmem_cache_alloc() objects 2023-03-29 10:35:41 +02:00
slab.c mm: vmscan: refactor updating current->reclaim_state 2023-04-18 16:30:10 -07:00
slab.h - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
slub.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
sparse-vmemmap.c mm/vmemmap/devdax: fix kernel crash when probing devdax devices 2023-04-18 16:30:09 -07:00
sparse.c sparse: remove unnecessary 0 values from rc 2023-04-21 14:52:05 -07:00
swap_cgroup.c mm: memcontrol: don't allocate cgroup swap arrays when memcg is disabled 2022-10-03 14:03:36 -07:00
swap_slots.c mm/swap: convert put_swap_page() to put_swap_folio() 2022-10-03 14:02:46 -07:00
swap_state.c mm: return an ERR_PTR from __filemap_get_folio 2023-04-05 19:42:42 -07:00
swap.c mm: swap: fix performance regression on sparsetruncate-tiny 2023-04-16 10:41:24 -07:00
swap.h mm: remove the __swap_writepage return value 2023-02-02 22:33:33 -08:00
swapfile.c sync mm-stable with mm-hotfixes-stable to pick up depended-upon upstream changes 2023-04-16 12:31:58 -07:00
truncate.c mm: return an ERR_PTR from __filemap_get_folio 2023-04-05 19:42:42 -07:00
usercopy.c mm: Fix copy_from_user_nofault(). 2023-04-12 17:36:23 -07:00
userfaultfd.c userfaultfd: use helper function range_in_vma() 2023-04-21 14:52:02 -07:00
util.c mm: uninline kstrdup() 2023-04-08 13:45:37 -07:00
vmalloc.c mm: vmalloc: rename addr_to_vb_xarray() function 2023-04-18 16:29:48 -07:00
vmpressure.c
vmscan.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00
vmstat.c mm: introduce per-VMA lock statistics 2023-04-05 20:03:01 -07:00
workingset.c mm: workingset: update description of the source file 2023-04-18 16:30:11 -07:00
z3fold.c mm: remove PageMovable export 2023-01-18 17:12:57 -08:00
zbud.c zpool: clean out dead code 2022-12-11 18:12:10 -08:00
zpool.c zpool: remove MODULE_LICENSE in non-modules 2023-04-13 13:13:54 -07:00
zsmalloc.c zsmalloc: allow only one active pool compaction context 2023-04-21 14:52:04 -07:00
zswap.c - Nick Piggin's "shoot lazy tlbs" series, to improve the peformance of 2023-04-27 19:42:02 -07:00