From: Fernando Luis Vazquez Cao <fernando@intellilink.co.jp>
To: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: linux-kernel@vger.kernel.org, fastboot@lists.osdl.org
Subject: [PATCH 4/4] stack overflow safe kdump (i386) - fault
Date: Tue, 29 Nov 2005 03:01:05 +0900 [thread overview]
Message-ID: <1133200865.2425.103.camel@localhost.localdomain> (raw)
When we have a bloated stack it is likely that it ends up making an
invalid memory access that causes a page fault. Take this case into
account in the page fault code.
---
diff -urNp linux-2.6.15-rc2/arch/i386/mm/fault.c
linux-2.6.15-rc2-sov/arch/i386/mm/fault.c
--- linux-2.6.15-rc2/arch/i386/mm/fault.c 2005-11-29 01:46:34.000000000
+0900
+++ linux-2.6.15-rc2-sov/arch/i386/mm/fault.c 2005-11-29
01:48:21.000000000 +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
reply other threads:[~2005-11-28 18:05 UTC|newest]
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