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powerpc: Fix PTE page address mismatch in pgtable ctor/dtor 

In pte_alloc_one(), pgtable_page_ctor() is passed an address that has
not been converted by page_address() to the newly allocated PTE page.

When the PTE is freed, __pte_free_tlb() calls pgtable_page_dtor()
with an address to the PTE page that has been converted by page_address().
The mismatch in the PTE's page address causes pgtable_page_dtor() to access
invalid memory, so resources for that PTE (such as the page lock) is not
properly cleaned up.

On PPC32, only SMP kernels are affected.

On PPC64, only SMP kernels with 4K page size are affected.

This bug was introduced by commit d614bb0412
"powerpc: Move the pte free routines from common header".

On a preempt-rt kernel, a spinlock is dynamically allocated for each
PTE in pgtable_page_ctor().  When the PTE is freed, calling
pgtable_page_dtor() with a mismatched page address causes a memory leak,
as the pointer to the PTE's spinlock is bogus.

On mainline, there isn't any immediately obvious symptoms, but the
problem still exists here.

Fixes: d614bb0412 "powerpc: Move the pte free routes from common header"
Cc: Paul Mackerras <paulus@samba.org>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: linux-stable <stable@vger.kernel.org> # v3.10+
Signed-off-by: Hong H. Pham <hong.pham@windriver.com>
Reviewed-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Hong H. Pham 2013-12-07 09:06:33 -05:00 committed by Benjamin Herrenschmidt
parent 1b429835be
commit cf77ee5436
2 changed files with 4 additions and 8 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

6
arch/powerpc/include/asm/pgalloc-32.h
View File

@ -84,10 +84,8 @@ static inline void pgtable_free_tlb(struct mmu_gather *tlb,
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
unsigned long address)
{
struct page *page = page_address(table);
tlb_flush_pgtable(tlb, address);
pgtable_page_dtor(page);
pgtable_free_tlb(tlb, page, 0);
pgtable_page_dtor(table);
pgtable_free_tlb(tlb, page_address(table), 0);
}
#endif /* _ASM_POWERPC_PGALLOC_32_H */

6
arch/powerpc/include/asm/pgalloc-64.h
View File

@ -148,11 +148,9 @@ static inline void pgtable_free_tlb(struct mmu_gather *tlb,
static inline void __pte_free_tlb(struct mmu_gather *tlb, pgtable_t table,
unsigned long address)
{
struct page *page = page_address(table);
tlb_flush_pgtable(tlb, address);
pgtable_page_dtor(page);
pgtable_free_tlb(tlb, page, 0);
pgtable_page_dtor(table);
pgtable_free_tlb(tlb, page_address(table), 0);
}
#else /* if CONFIG_PPC_64K_PAGES */