Messages in this thread | | | Subject | Re: [PATCH v3] powerpc/64s/pgtable: fix an undefined behaviour | From | Qian Cai <> | Date | Sat, 9 May 2020 09:19:09 -0400 |
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> On Mar 6, 2020, at 1:56 AM, Christophe Leroy <christophe.leroy@c-s.fr> wrote: > > > > Le 06/03/2020 à 05:48, Qian Cai a écrit : >> 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> > > Reviewed-by: Christophe Leroy <christophe.leroy@c-s.fr>
Michael, can you take a look at this patch when you have a chance? It looks falling through the cracks.
> >> --- >> v3: convert pud_index() etc to static inline functions. >> v2: convert pud_offset() etc to static inline functions. >> arch/powerpc/include/asm/book3s/64/pgtable.h | 23 ++++++++++++++++---- >> 1 file changed, 19 insertions(+), 4 deletions(-) >> diff --git a/arch/powerpc/include/asm/book3s/64/pgtable.h b/arch/powerpc/include/asm/book3s/64/pgtable.h >> index 201a69e6a355..bd432c6706b9 100644 >> --- a/arch/powerpc/include/asm/book3s/64/pgtable.h >> +++ b/arch/powerpc/include/asm/book3s/64/pgtable.h >> @@ -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
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