Re: Reading /proc/kcore causes a BUG()

KAMEZAWA Hiroyuki
2009-09-07T06:16:26Z

On Mon, 7 Sep 2009 09:38:56 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> > That's a lot of stuff for 2.6.31. Is there some simple quickfix we can do?
> >
> I don't like this patch. But here, my 1st version which wasn't sent out.
> -Kame

Fixed warnings. (I confirmed this patch works well on x86-64.)
==
To access vmalloc area which may have memory holes, copy_from_user is
useful. By this,
# cat /proc/kcore > /dev/null
will not panic.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
fs/proc/kcore.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)

Index: linux-2.6.31-rc8/fs/proc/kcore.c
===================================================================
--- linux-2.6.31-rc8.orig/fs/proc/kcore.c
+++ linux-2.6.31-rc8/fs/proc/kcore.c
@@ -361,7 +361,13 @@ read_kcore(struct file *file, char __use
/* don't dump ioremap'd stuff! (TA) */
if (m->flags & VM_IOREMAP)
continue;
- memcpy(elf_buf + (vmstart - start),
+ /*
+ * we may access memory holes, then use
+ * ex_table. checking return value just for
+ * avoid warnings.
+ */
+ vmsize = __copy_from_user_inatomic(
+ elf_buf + (vmstart - start),
(char *)vmstart, vmsize);
}
read_unlock(&vmlist_lock);