Messages in this thread Patch in this message | | | Subject | [PATCH 3/5] stack overflow safe kdump (2.6.16-rc1-i386) - fault | From | Fernando Luis Vazquez Cao <> | Date | Wed, 25 Jan 2006 15:53:20 +0900 |
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When we have a bloated stack it is likely that it ends up making an invalid memory access that in turn causes a page fault. Take this case into account in the page fault code.
Signed-off-by: Fernando Vazquez <fernando@intellilink.co.jp> ---
diff -urNp linux-2.6.16-rc1/arch/i386/mm/fault.c linux-2.6.16-rc1-sov/arch/i386/mm/fault.c --- linux-2.6.16-rc1/arch/i386/mm/fault.c 2006-01-03 12:21:10.000000000 +0900 +++ linux-2.6.16-rc1-sov/arch/i386/mm/fault.c 2006-01-25 14:43:13.000000000 +0900 @@ -245,6 +245,11 @@ fastcall void __kprobes do_page_fault(st local_irq_enable(); tsk = current; + /* We may have invalid '*current' due to a stack overflow. */ + if (!virt_addr_valid(tsk)) { + printk("do_page_fault: Discarding invalid 'current' struct task_struct * = 0x%p\n", tsk); + tsk = NULL; + } si_code = SEGV_MAPERR; @@ -271,7 +276,14 @@ fastcall void __kprobes do_page_fault(st goto bad_area_nosemaphore; } - mm = tsk->mm; + mm = NULL; + /* We may have invalid 'tsk' due to a i386 stack overflow */ + if (tsk) + mm = tsk->mm; + if (mm && !virt_addr_valid(mm)) { + printk("do_page_fault: Discarding invalid current->mm struct mm_struct * = 0x%p\n", mm); + mm = NULL; + } /* * If we're in an interrupt, have no user context or are running in an
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