From: "Nicolas S. Dade" <n-dade@nsd.dyndns.org>
To: user-mode-linux-devel@lists.sourceforge.net
Subject: [uml-devel] fix SEGV in handle_page_fault() when current->mm is NULL
Date: Thu, 24 May 2007 02:29:04 -0700 [thread overview]
Message-ID: <20070524092904.GB3768@sparc20.esperanza> (raw)
[-- Attachment #1: Type: text/plain, Size: 275 bytes --]
In a non-uml kernel a get_user() when current->mm is NULL (kernel thread, or
userspace process being torn down) returns error. In uml it SEGVs. The bug is
that handle_page_fault() does not check for NULL before using mm. The
trivial attached patch fixes this.
-Nicolas Dade
[-- Attachment #2: fix.patch --]
[-- Type: text/plain, Size: 375 bytes --]
--- linux-2.6.21.2/arch/um/kernel/trap.c.orig 2007-05-24 02:22:42.000000000 -0700
+++ linux-2.6.21.2/arch/um/kernel/trap.c 2007-05-24 02:23:45.000000000 -0700
@@ -51,6 +51,9 @@
* fail. */
if (in_atomic())
goto out_nosemaphore;
+ /* If we have no user-space just fail */
+ if (!mm)
+ goto out_nosemaphore;
down_read(&mm->mmap_sem);
vma = find_vma(mm, address);
[-- Attachment #3: Type: text/plain, Size: 286 bytes --]
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next reply other threads:[~2007-05-24 9:29 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-05-24 9:29 Nicolas S. Dade [this message]
2007-05-26 11:02 ` [uml-devel] fix SEGV in handle_page_fault() when current->mm is NULL Blaisorblade
2007-05-30 15:30 ` Jeff Dike
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