* [PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE
@ 2014-07-10 8:42 Madhusudanan Kandasamy
2014-07-10 13:59 ` Brian W Hart
0 siblings, 1 reply; 2+ messages in thread
From: Madhusudanan Kandasamy @ 2014-07-10 8:42 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Paul Mackerras, linux-kernel,
linuxppc-dev, Stephen Rothwell
V2 : Rewritten to avoid helper function as suggested by Stephen Rothwell.
remap_4k_pfn() silently truncates upper bits of input 4K PFN if
it cannot be contained in PTE. This leads invalid memory mapping
and could result in a system crash when the memory is accessed.
This patch fails remap_4k_pfn() and returns -EINVAL if the input
4K PFN cannot be contained in PTE.
Signed-off-by: Madhusudanan Kandasamy <kmadhu@linux.vnet.ibm.com>
---
arch/powerpc/include/asm/pte-hash64-64k.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/pte-hash64-64k.h b/arch/powerpc/include/asm/pte-hash64-64k.h
index d836d94..b5178e4 100644
--- a/arch/powerpc/include/asm/pte-hash64-64k.h
+++ b/arch/powerpc/include/asm/pte-hash64-64k.h
@@ -75,7 +75,8 @@
(((pte) & _PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K)
#define remap_4k_pfn(vma, addr, pfn, prot) \
- remap_pfn_range((vma), (addr), (pfn), PAGE_SIZE, \
+ WARN_ON((pfn >= (1UL << (64 - PTE_RPN_SHIFT)))) ? -EINVAL : \
+ remap_pfn_range((vma), (addr), (pfn), PAGE_SIZE, \
__pgprot(pgprot_val((prot)) | _PAGE_4K_PFN))
#endif /* __ASSEMBLY__ */
--
2.0.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE
2014-07-10 8:42 [PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE Madhusudanan Kandasamy
@ 2014-07-10 13:59 ` Brian W Hart
0 siblings, 0 replies; 2+ messages in thread
From: Brian W Hart @ 2014-07-10 13:59 UTC (permalink / raw)
To: linuxppc-dev, linuxppc-dev
On Thu, Jul 10, 2014 at 02:12:19PM +0530, Madhusudanan Kandasamy wrote:
> V2 : Rewritten to avoid helper function as suggested by Stephen Rothwell.
> remap_4k_pfn() silently truncates upper bits of input 4K PFN if
> it cannot be contained in PTE. This leads invalid memory mapping
> and could result in a system crash when the memory is accessed.
> This patch fails remap_4k_pfn() and returns -EINVAL if the input
> 4K PFN cannot be contained in PTE.
>
> Signed-off-by: Madhusudanan Kandasamy <kmadhu@linux.vnet.ibm.com>
> ---
> arch/powerpc/include/asm/pte-hash64-64k.h | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/include/asm/pte-hash64-64k.h b/arch/powerpc/include/asm/pte-hash64-64k.h
> index d836d94..b5178e4 100644
> --- a/arch/powerpc/include/asm/pte-hash64-64k.h
> +++ b/arch/powerpc/include/asm/pte-hash64-64k.h
> @@ -75,7 +75,8 @@
> (((pte) & _PAGE_COMBO)? MMU_PAGE_4K: MMU_PAGE_64K)
>
> #define remap_4k_pfn(vma, addr, pfn, prot) \
> - remap_pfn_range((vma), (addr), (pfn), PAGE_SIZE, \
> + WARN_ON((pfn >= (1UL << (64 - PTE_RPN_SHIFT)))) ? -EINVAL : \
> + remap_pfn_range((vma), (addr), (pfn), PAGE_SIZE, \
> __pgprot(pgprot_val((prot)) | _PAGE_4K_PFN))
>
> #endif /* __ASSEMBLY__ */
> --
> 2.0.1
Chatted with Madhu. He'll send a new version that adds some
parentheses to protect 'pfn' inside the macro and the entire macro
against use cases like:
!remap_4k_pfn(...)
brian
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2014-07-10 8:42 [PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE Madhusudanan Kandasamy
2014-07-10 13:59 ` Brian W Hart
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