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powerpc/64s/pgtable: fix an undefined behaviour 

[ Upstream commit c2e929b18c ]

Booting a power9 server with hash MMU could trigger an undefined
behaviour because pud_offset(p4d, 0) will do,

0 >> (PAGE_SHIFT:16 + PTE_INDEX_SIZE:8 + H_PMD_INDEX_SIZE:10)

Fix it by converting pud_index() and friends to static inline
functions.

UBSAN: shift-out-of-bounds in arch/powerpc/mm/ptdump/ptdump.c:282:15
shift exponent 34 is too large for 32-bit type 'int'
CPU: 6 PID: 1 Comm: swapper/0 Not tainted 5.6.0-rc4-next-20200303+ #13
Call Trace:
dump_stack+0xf4/0x164 (unreliable)
ubsan_epilogue+0x18/0x78
__ubsan_handle_shift_out_of_bounds+0x160/0x21c
walk_pagetables+0x2cc/0x700
walk_pud at arch/powerpc/mm/ptdump/ptdump.c:282
(inlined by) walk_pagetables at arch/powerpc/mm/ptdump/ptdump.c:311
ptdump_check_wx+0x8c/0xf0
mark_rodata_ro+0x48/0x80
kernel_init+0x74/0x194
ret_from_kernel_thread+0x5c/0x74

Suggested-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Qian Cai <cai@lca.pw>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Link: https://lore.kernel.org/r/20200306044852.3236-1-cai@lca.pw
Signed-off-by: Sasha Levin <sashal@kernel.org>
5.4-rM2-2.2.x-imx-squashed
Qian Cai 2020-03-05 23:48:52 -05:00 committed by Greg Kroah-Hartman
parent a7ba81f26d
commit 96cd8d249a
1 changed files with 19 additions and 4 deletions
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23
arch/powerpc/include/asm/book3s/64/pgtable.h
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@ -998,10 +998,25 @@ extern struct page *pgd_page(pgd_t pgd);
#define pud_page_vaddr(pud) __va(pud_val(pud) & ~PUD_MASKED_BITS)
#define pgd_page_vaddr(pgd) __va(pgd_val(pgd) & ~PGD_MASKED_BITS)
#define pgd_index(address) (((address) >> (PGDIR_SHIFT)) & (PTRS_PER_PGD - 1))
#define pud_index(address) (((address) >> (PUD_SHIFT)) & (PTRS_PER_PUD - 1))
#define pmd_index(address) (((address) >> (PMD_SHIFT)) & (PTRS_PER_PMD - 1))
#define pte_index(address) (((address) >> (PAGE_SHIFT)) & (PTRS_PER_PTE - 1))
static inline unsigned long pgd_index(unsigned long address)
{
return (address >> PGDIR_SHIFT) & (PTRS_PER_PGD - 1);
}
static inline unsigned long pud_index(unsigned long address)
{
return (address >> PUD_SHIFT) & (PTRS_PER_PUD - 1);
}
static inline unsigned long pmd_index(unsigned long address)
{
return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
}
static inline unsigned long pte_index(unsigned long address)
{
return (address >> PAGE_SHIFT) & (PTRS_PER_PTE - 1);
}
/*
* Find an entry in a page-table-directory. We combine the address region