forked from luck/tmp_suning_uos_patched
5b1ba9e30c
The current page table walk code in pageattr.c only checks for large pages while walking the kernel page table, but happily assumes that everything else is just fine. Add more checks so we never access invalid memory regions. Reviewed-by: Gerald Schaefer <gerald.schaefer@de.ibm.com> Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com> Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
76 lines
1.4 KiB
C
76 lines
1.4 KiB
C
/*
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* Copyright IBM Corp. 2011
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* Author(s): Jan Glauber <jang@linux.vnet.ibm.com>
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*/
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#include <linux/module.h>
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#include <linux/mm.h>
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#include <linux/hugetlb.h>
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#include <asm/cacheflush.h>
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#include <asm/pgtable.h>
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static pte_t *walk_page_table(unsigned long addr)
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{
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pgd_t *pgdp;
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pud_t *pudp;
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pmd_t *pmdp;
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pte_t *ptep;
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pgdp = pgd_offset_k(addr);
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if (pgd_none(*pgdp))
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return NULL;
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pudp = pud_offset(pgdp, addr);
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if (pud_none(*pudp))
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return NULL;
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pmdp = pmd_offset(pudp, addr);
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if (pmd_none(*pmdp) || pmd_large(*pmdp))
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return NULL;
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ptep = pte_offset_kernel(pmdp, addr);
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if (pte_none(*ptep))
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return NULL;
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return ptep;
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}
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static void change_page_attr(unsigned long addr, int numpages,
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pte_t (*set) (pte_t))
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{
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pte_t *ptep, pte;
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int i;
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for (i = 0; i < numpages; i++) {
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ptep = walk_page_table(addr);
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if (WARN_ON_ONCE(!ptep))
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break;
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pte = *ptep;
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pte = set(pte);
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__ptep_ipte(addr, ptep);
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*ptep = pte;
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addr += PAGE_SIZE;
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}
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}
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int set_memory_ro(unsigned long addr, int numpages)
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{
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change_page_attr(addr, numpages, pte_wrprotect);
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_ro);
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int set_memory_rw(unsigned long addr, int numpages)
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{
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change_page_attr(addr, numpages, pte_mkwrite);
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_rw);
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/* not possible */
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int set_memory_nx(unsigned long addr, int numpages)
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{
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return 0;
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}
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EXPORT_SYMBOL_GPL(set_memory_nx);
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int set_memory_x(unsigned long addr, int numpages)
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{
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return 0;
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}
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