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Groups > linux.kernel > #1443750
| From | Andy Lutomirski <luto@kernel.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 06/11] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm |
| Date | 2016-07-14 22:30 +0200 |
| Message-ID | <rUVqG-5SB-43@gated-at.bofh.it> (permalink) |
| References | <rUVqF-5SB-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
If we get a vmalloc fault while current->active_mm->pgd doesn't match CR3, we'll crash without this change. I've seen this failure mode on heavily instrumented kernels with virtually mapped stacks. Signed-off-by: Andy Lutomirski <luto@kernel.org> --- arch/x86/mm/fault.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c index 7d1fa7cd2374..ca44e2e7fd00 100644 --- a/arch/x86/mm/fault.c +++ b/arch/x86/mm/fault.c @@ -439,7 +439,7 @@ static noinline int vmalloc_fault(unsigned long address) * happen within a race in page table update. In the later * case just flush: */ - pgd = pgd_offset(current->active_mm, address); + pgd = (pgd_t *)__va(read_cr3()) + pgd_index(address); pgd_ref = pgd_offset_k(address); if (pgd_none(*pgd_ref)) return -1; -- 2.7.4
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[PATCH 00/11] x86: misc prep patches for virtually mapped stacks Andy Lutomirski <luto@kernel.org> - 2016-07-14 22:30 +0200
[PATCH 09/11] x86: Move addr_limit to thread_struct Andy Lutomirski <luto@kernel.org> - 2016-07-14 22:30 +0200
[tip:x86/mm] x86/uaccess: Move thread_info::addr_limit to thread_struct tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-07-15 14:10 +0200
[PATCH 06/11] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm Andy Lutomirski <luto@kernel.org> - 2016-07-14 22:30 +0200
[tip:x86/mm] x86/mm/64: In vmalloc_fault(), use CR3 instead of current->active_mm tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-07-15 14:10 +0200
[PATCH 11/11] x86/smp: Remove unnecessary initialization of thread_info::cpu Andy Lutomirski <luto@kernel.org> - 2016-07-14 22:30 +0200
[tip:x86/mm] x86/smp: Remove unnecessary initialization of thread_info::cpu tip-bot for Andy Lutomirski <tipbot@zytor.com> - 2016-07-15 14:10 +0200
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