CVE-2024-56628

In the Linux kernel, the following vulnerability has been resolved:

LoongArch: Add architecture specific huge_pte_clear()

When executing mm selftests run_vmtests.sh, there is such an error:

BUG: Bad page state in process uffd-unit-tests pfn:00000

page: refcount:0 mapcount:0 mapping:0000000000000000 index:0x0 pfn:0x0

flags: 0xffff0000002000(reserved|node=0|zone=0|lastcpupid=0xffff)

raw: 00ffff0000002000 ffffbf0000000008 ffffbf0000000008 0000000000000000

raw: 0000000000000000 0000000000000000 00000000ffffffff 0000000000000000

page dumped because: PAGE_FLAGS_CHECK_AT_FREE flag(s) set

Modules linked in: snd_seq_dummy snd_seq snd_seq_device rfkill vfat fat

virtio_balloon efi_pstore virtio_net pstore net_failover failover fuse

nfnetlink virtio_scsi virtio_gpu virtio_dma_buf dm_multipath efivarfs

CPU: 2 UID: 0 PID: 1913 Comm: uffd-unit-tests Not tainted 6.12.0 #184

Hardware name: QEMU QEMU Virtual Machine, BIOS unknown 2/2/2022

Stack : 900000047c8ac000 0000000000000000 9000000000223a7c 900000047c8ac000

900000047c8af690 900000047c8af698 0000000000000000 900000047c8af7d8

900000047c8af7d0 900000047c8af7d0 900000047c8af5b0 0000000000000001

0000000000000001 900000047c8af698 10b3c7d53da40d26 0000010000000000

0000000000000022 0000000fffffffff fffffffffe000000 ffff800000000000

000000000000002f 0000800000000000 000000017a6d4000 90000000028f8940

0000000000000000 0000000000000000 90000000025aa5e0 9000000002905000

0000000000000000 90000000028f8940 ffff800000000000 0000000000000000

0000000000000000 0000000000000000 9000000000223a94 000000012001839c

00000000000000b0 0000000000000004 0000000000000000 0000000000071c1d

...

Call Trace:

[<9000000000223a94>] show_stack+0x5c/0x180

[<9000000001c3fd64>] dump_stack_lvl+0x6c/0xa0

[<900000000056aa08>] bad_page+0x1a0/0x1f0

[<9000000000574978>] free_unref_folios+0xbf0/0xd20

[<90000000004e65cc>] folios_put_refs+0x1a4/0x2b8

[<9000000000599a0c>] free_pages_and_swap_cache+0x164/0x260

[<9000000000547698>] tlb_batch_pages_flush+0xa8/0x1c0

[<9000000000547f30>] tlb_finish_mmu+0xa8/0x218

[<9000000000543cb8>] exit_mmap+0x1a0/0x360

[<9000000000247658>] __mmput+0x78/0x200

[<900000000025583c>] do_exit+0x43c/0xde8

[<9000000000256490>] do_group_exit+0x68/0x110

[<9000000000256554>] sys_exit_group+0x1c/0x20

[<9000000001c413b4>] do_syscall+0x94/0x130

[<90000000002216d8>] handle_syscall+0xb8/0x158

Disabling lock debugging due to kernel taint

BUG: non-zero pgtables_bytes on freeing mm: -16384

On LoongArch system, invalid huge pte entry should be invalid_pte_table

or a single _PAGE_HUGE bit rather than a zero value. And it should be

the same with invalid pmd entry, since pmd_none() is called by function

free_pgd_range() and pmd_none() return 0 by huge_pte_clear(). So single

_PAGE_HUGE bit is also treated as a valid pte table and free_pte_range()

will be called in free_pmd_range().

free_pmd_range()

pmd = pmd_offset(pud, addr);

do {

next = pmd_addr_end(addr, end);

if (pmd_none_or_clear_bad(pmd))

continue;

free_pte_range(tlb, pmd, addr);

} while (pmd++, addr = next, addr != end);

Here invalid_pte_table is used for both invalid huge pte entry and

pmd entry.