Re: [PATCH] mm: fix possible OOB in numa_rebuild_large_mapping()

[David Hildenbrand <david@redhat.com>]

On 07.06.24 12:32, Kefeng Wang wrote:
> The large folio is mapped with folio size aligned virtual address during
> the pagefault, eg, 'addr = ALIGN_DOWN(vmf->address, nr_pages * PAGE_SIZE)'
> in do_anonymous_page(), but after the mremap(), the virtual address only
> require PAGE_SIZE aligned, also pte is moved to new in move_page_tables(),
> then traverse the new pte in numa_rebuild_large_mapping() will hint the
> following issue,
> 
>     Unable to handle kernel paging request at virtual address 00000a80c021a788
>     Mem abort info:
>       ESR = 0x0000000096000004
>       EC = 0x25: DABT (current EL), IL = 32 bits
>       SET = 0, FnV = 0
>       EA = 0, S1PTW = 0
>       FSC = 0x04: level 0 translation fault
>     Data abort info:
>       ISV = 0, ISS = 0x00000004, ISS2 = 0x00000000
>       CM = 0, WnR = 0, TnD = 0, TagAccess = 0
>       GCS = 0, Overlay = 0, DirtyBit = 0, Xs = 0
>     user pgtable: 4k pages, 48-bit VAs, pgdp=00002040341a6000
>     [00000a80c021a788] pgd=0000000000000000, p4d=0000000000000000
>     Internal error: Oops: 0000000096000004 [#1] SMP
>     ...
>     CPU: 76 PID: 15187 Comm: git Kdump: loaded Tainted: G        W          6.10.0-rc2+ #209
>     Hardware name: Huawei TaiShan 2280 V2/BC82AMDD, BIOS 1.79 08/21/2021
>     pstate: 60400009 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
>     pc : numa_rebuild_large_mapping+0x338/0x638
>     lr : numa_rebuild_large_mapping+0x320/0x638
>     sp : ffff8000b41c3b00
>     x29: ffff8000b41c3b30 x28: ffff8000812a0000 x27: 00000000000a8000
>     x26: 00000000000000a8 x25: 0010000000000001 x24: ffff20401c7170f0
>     x23: 0000ffff33a1e000 x22: 0000ffff33a76000 x21: ffff20400869eca0
>     x20: 0000ffff33976000 x19: 00000000000000a8 x18: ffffffffffffffff
>     x17: 0000000000000000 x16: 0000000000000020 x15: ffff8000b41c36a8
>     x14: 0000000000000000 x13: 205d373831353154 x12: 5b5d333331363732
>     x11: 000000000011ff78 x10: 000000000011ff10 x9 : ffff800080273f30
>     x8 : 000000320400869e x7 : c0000000ffffd87f x6 : 00000000001e6ba8
>     x5 : ffff206f3fb5af88 x4 : 0000000000000000 x3 : 0000000000000000
>     x2 : 0000000000000000 x1 : fffffdffc0000000 x0 : 00000a80c021a780
>     Call trace:
>      numa_rebuild_large_mapping+0x338/0x638
>      do_numa_page+0x3e4/0x4e0
>      handle_pte_fault+0x1bc/0x238
>      __handle_mm_fault+0x20c/0x400
>      handle_mm_fault+0xa8/0x288
>      do_page_fault+0x124/0x498
>      do_translation_fault+0x54/0x80
>      do_mem_abort+0x4c/0xa8
>      el0_da+0x40/0x110
>      el0t_64_sync_handler+0xe4/0x158
>      el0t_64_sync+0x188/0x190

Do you have an easy reproducer that we can use to reproduce+verify this 
issue? The description above indicates to me that this should not be too 
complicated to write :)

-- 
Cheers,

David / dhildenb