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Peter Anvin" , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Thomas Gleixner , Borislav Petkov , "Edgecombe, Rick P" , Oleg Vasilev , Arthur Petukhovsky , Stefan Radig , Misha Sakhnov References: <0ce5e150-19e0-457f-bec3-ee031c0be7e7@neon.tech> Content-Language: en-US In-Reply-To: <0ce5e150-19e0-457f-bec3-ee031c0be7e7@neon.tech> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit During memory hotplug, allocation failures in phys_*_init() aren't handled, which results in a null pointer dereference, if they occur. To handle that, change phys_pud_init() and similar functions to return allocation errors via ERR_PTR() and check for that in arch_add_memory(). Signed-off-by: Em Sharnoff --- Changelog: - v2: switch from special-casing zero value to using ERR_PTR() --- arch/x86/mm/init.c | 6 ++++- arch/x86/mm/init_64.c | 54 +++++++++++++++++++++++++++++++++++++++---- 2 files changed, 55 insertions(+), 5 deletions(-) diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index bfa444a7dbb0..82dd5ce03dd6 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -533,6 +533,7 @@ bool pfn_range_is_mapped(unsigned long start_pfn, unsigned long end_pfn) * Setup the direct mapping of the physical memory at PAGE_OFFSET. * This runs before bootmem is initialized and gets pages directly from * the physical memory. To access them they are temporarily mapped. + * Allocation errors are returned with ERR_PTR. */ unsigned long __ref init_memory_mapping(unsigned long start, unsigned long end, pgprot_t prot) @@ -547,10 +548,13 @@ unsigned long __ref init_memory_mapping(unsigned long start, memset(mr, 0, sizeof(mr)); nr_range = split_mem_range(mr, 0, start, end); - for (i = 0; i < nr_range; i++) + for (i = 0; i < nr_range; i++) { ret = kernel_physical_mapping_init(mr[i].start, mr[i].end, mr[i].page_size_mask, prot); + if (IS_ERR(ret)) + return ret; + } add_pfn_range_mapped(start >> PAGE_SHIFT, ret >> PAGE_SHIFT); diff --git a/arch/x86/mm/init_64.c b/arch/x86/mm/init_64.c index 7c4f6f591f2b..3ab261aa8eff 100644 --- a/arch/x86/mm/init_64.c +++ b/arch/x86/mm/init_64.c @@ -502,7 +502,8 @@ phys_pte_init(pte_t *pte_page, unsigned long paddr, unsigned long paddr_end, /* * Create PMD level page table mapping for physical addresses. The virtual * and physical address have to be aligned at this level. - * It returns the last physical address mapped. + * It returns the last physical address mapped. Allocation errors are + * returned with ERR_PTR. */ static unsigned long __meminit phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end, @@ -572,7 +573,14 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end, } pte = alloc_low_page(); + if (!pte) + return (unsigned long)ERR_PTR(-ENOMEM); paddr_last = phys_pte_init(pte, paddr, paddr_end, new_prot, init); + /* + * phys_{ppmd,pud,p4d}_init return allocation errors via ERR_PTR. + * phys_pte_init makes no allocations, so should not error. + */ + BUG_ON(IS_ERR(paddr_last)); spin_lock(&init_mm.page_table_lock); pmd_populate_kernel_init(&init_mm, pmd, pte, init); @@ -586,7 +594,8 @@ phys_pmd_init(pmd_t *pmd_page, unsigned long paddr, unsigned long paddr_end, * Create PUD level page table mapping for physical addresses. The virtual * and physical address do not have to be aligned at this level. KASLR can * randomize virtual addresses up to this level. - * It returns the last physical address mapped. + * It returns the last physical address mapped. Allocation errors are + * returned with ERR_PTR. */ static unsigned long __meminit phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end, @@ -623,6 +632,8 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end, paddr_end, page_size_mask, prot, init); + if (IS_ERR(paddr_last)) + return paddr_last; continue; } /* @@ -658,12 +669,22 @@ phys_pud_init(pud_t *pud_page, unsigned long paddr, unsigned long paddr_end, } pmd = alloc_low_page(); + if (!pmd) + return (unsigned long)ERR_PTR(-ENOMEM); paddr_last = phys_pmd_init(pmd, paddr, paddr_end, page_size_mask, prot, init); + /* + * We might have IS_ERR(paddr_last) if allocation failed, but we should + * still update pud before bailing, so that subsequent retries can pick + * up on progress (here and in phys_pmd_init) without leaking pmd. + */ spin_lock(&init_mm.page_table_lock); pud_populate_init(&init_mm, pud, pmd, init); spin_unlock(&init_mm.page_table_lock); + + if (IS_ERR(paddr_last)) + return paddr_last; } update_page_count(PG_LEVEL_1G, pages); @@ -707,16 +728,26 @@ phys_p4d_init(p4d_t *p4d_page, unsigned long paddr, unsigned long paddr_end, pud = pud_offset(p4d, 0); paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end), page_size_mask, prot, init); + if (IS_ERR(paddr_last)) + return paddr_last; continue; } pud = alloc_low_page(); + if (!pud) + return (unsigned long)ERR_PTR(-ENOMEM); paddr_last = phys_pud_init(pud, paddr, __pa(vaddr_end), page_size_mask, prot, init); spin_lock(&init_mm.page_table_lock); p4d_populate_init(&init_mm, p4d, pud, init); spin_unlock(&init_mm.page_table_lock); + + /* + * Bail only after updating p4d to keep progress from pud across retries. + */ + if (IS_ERR(paddr_last)) + return paddr_last; } return paddr_last; @@ -748,10 +779,14 @@ __kernel_physical_mapping_init(unsigned long paddr_start, __pa(vaddr_end), page_size_mask, prot, init); + if (IS_ERR(paddr_last)) + return paddr_last; continue; } p4d = alloc_low_page(); + if (!p4d) + return (unsigned long)ERR_PTR(-ENOMEM); paddr_last = phys_p4d_init(p4d, __pa(vaddr), __pa(vaddr_end), page_size_mask, prot, init); @@ -763,6 +798,13 @@ __kernel_physical_mapping_init(unsigned long paddr_start, (pud_t *) p4d, init); spin_unlock(&init_mm.page_table_lock); + + /* + * Bail only after updating pgd/p4d to keep progress from p4d across retries. + */ + if (IS_ERR(paddr_last)) + return paddr_last; + pgd_changed = true; } @@ -777,7 +819,8 @@ __kernel_physical_mapping_init(unsigned long paddr_start, * Create page table mapping for the physical memory for specific physical * addresses. Note that it can only be used to populate non-present entries. * The virtual and physical addresses have to be aligned on PMD level - * down. It returns the last physical address mapped. + * down. It returns the last physical address mapped. Allocation errors are + * returned with ERR_PTR. */ unsigned long __meminit kernel_physical_mapping_init(unsigned long paddr_start, @@ -980,8 +1023,11 @@ int arch_add_memory(int nid, u64 start, u64 size, { unsigned long start_pfn = start >> PAGE_SHIFT; unsigned long nr_pages = size >> PAGE_SHIFT; + unsigned long ret = 0; - init_memory_mapping(start, start + size, params->pgprot); + ret = init_memory_mapping(start, start + size, params->pgprot); + if (IS_ERR(ret)) + return (int)PTR_ERR(ret); return add_pages(nid, start_pfn, nr_pages, params); } -- 2.39.5