diff options
| author | Chen Jingwen | 2021-12-29 11:52:26 +0800 |
|---|---|---|
| committer | Michael Ellerman | 2022-02-03 22:37:44 +1100 |
| commit | dd75080aa8409ce10d50fb58981c6b59bf8707d3 (patch) | |
| tree | 3a7382182f10aa1321118053890dc7212c5bc296 /arch/powerpc/mm | |
| parent | e414e2938ee26e734f19e92a60cd090ebaff37e6 (diff) | |
powerpc/kasan: Fix early region not updated correctly
The shadow's page table is not updated when PTE_RPN_SHIFT is 24
and PAGE_SHIFT is 12. It not only causes false positives but
also false negative as shown the following text.
Fix it by bringing the logic of kasan_early_shadow_page_entry here.
1. False Positive:
==================================================================
BUG: KASAN: vmalloc-out-of-bounds in pcpu_alloc+0x508/0xa50
Write of size 16 at addr f57f3be0 by task swapper/0/1
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.15.0-12267-gdebe436e77c7 #1
Call Trace:
[c80d1c20] [c07fe7b8] dump_stack_lvl+0x4c/0x6c (unreliable)
[c80d1c40] [c02ff668] print_address_description.constprop.0+0x88/0x300
[c80d1c70] [c02ff45c] kasan_report+0x1ec/0x200
[c80d1cb0] [c0300b20] kasan_check_range+0x160/0x2f0
[c80d1cc0] [c03018a4] memset+0x34/0x90
[c80d1ce0] [c0280108] pcpu_alloc+0x508/0xa50
[c80d1d40] [c02fd7bc] __kmem_cache_create+0xfc/0x570
[c80d1d70] [c0283d64] kmem_cache_create_usercopy+0x274/0x3e0
[c80d1db0] [c2036580] init_sd+0xc4/0x1d0
[c80d1de0] [c00044a0] do_one_initcall+0xc0/0x33c
[c80d1eb0] [c2001624] kernel_init_freeable+0x2c8/0x384
[c80d1ef0] [c0004b14] kernel_init+0x24/0x170
[c80d1f10] [c001b26c] ret_from_kernel_thread+0x5c/0x64
Memory state around the buggy address:
f57f3a80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
f57f3b00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
>f57f3b80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
^
f57f3c00: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
f57f3c80: f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8 f8
==================================================================
2. False Negative (with KASAN tests):
==================================================================
Before fix:
ok 45 - kmalloc_double_kzfree
# vmalloc_oob: EXPECTATION FAILED at lib/test_kasan.c:1039
KASAN failure expected in "((volatile char *)area)[3100]", but none occurred
not ok 46 - vmalloc_oob
not ok 1 - kasan
==================================================================
After fix:
ok 1 - kasan
Fixes: cbd18991e24fe ("powerpc/mm: Fix an Oops in kasan_mmu_init()")
Cc: stable@vger.kernel.org # 5.4.x
Signed-off-by: Chen Jingwen <chenjingwen6@huawei.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20211229035226.59159-1-chenjingwen6@huawei.com
Diffstat (limited to 'arch/powerpc/mm')
| -rw-r--r-- | arch/powerpc/mm/kasan/kasan_init_32.c | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/arch/powerpc/mm/kasan/kasan_init_32.c b/arch/powerpc/mm/kasan/kasan_init_32.c index cf8770b1a692..f3e4d069e0ba 100644 --- a/arch/powerpc/mm/kasan/kasan_init_32.c +++ b/arch/powerpc/mm/kasan/kasan_init_32.c @@ -83,13 +83,12 @@ void __init kasan_update_early_region(unsigned long k_start, unsigned long k_end, pte_t pte) { unsigned long k_cur; - phys_addr_t pa = __pa(kasan_early_shadow_page); for (k_cur = k_start; k_cur != k_end; k_cur += PAGE_SIZE) { pmd_t *pmd = pmd_off_k(k_cur); pte_t *ptep = pte_offset_kernel(pmd, k_cur); - if ((pte_val(*ptep) & PTE_RPN_MASK) != pa) + if (pte_page(*ptep) != virt_to_page(lm_alias(kasan_early_shadow_page))) continue; __set_pte_at(&init_mm, k_cur, ptep, pte, 0); |