[PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE

Subsystems: linux for powerpc (32-bit and 64-bit), the rest

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2 messages, 2 authors, 2014-07-10 · open the first message on its own page

[PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE

From: Madhusudanan Kandasamy <hidden>
Date: 2014-07-10 08:42:31 

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 <redacted>
---
 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

Re: [PATCH V2] powerpc: Fail remap_4k_pfn() if PFN doesn't fit inside PTE

From: Brian W Hart <hidden>
Date: 2014-07-10 13:59:59 

On Thu, Jul 10, 2014 at 02:12:19PM +0530, Madhusudanan Kandasamy wrote:
quoted hunk
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 <redacted>
---
 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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