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 <[email protected]>
Signed-off-by: Qian Cai <[email protected]>
---
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
--
2.21.0 (Apple Git-122.2)
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 <[email protected]>
> Signed-off-by: Qian Cai <[email protected]>
Reviewed-by: Christophe Leroy <[email protected]>
> ---
>
> 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
>
> On Mar 6, 2020, at 1:56 AM, Christophe Leroy <[email protected]> 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 <[email protected]>
>> Signed-off-by: Qian Cai <[email protected]>
>
> Reviewed-by: Christophe Leroy <[email protected]>
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
On Thu, 5 Mar 2020 23:48:52 -0500, Qian Cai wrote:
> 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.
>
> [...]
Applied to powerpc/next.
[1/1] powerpc/64s/pgtable: fix an undefined behaviour
https://git.kernel.org/powerpc/c/c2e929b18cea6cbf71364f22d742d9aad7f4677a
cheers