Re: [RFC][PATCH v3 6/6] fix wrong get_user_pages usage in iovlock.c

KOSAKI Motohiro
2009-04-15T08:48:07Z

> > I would perhaps not fold gup_fast conversions into the same patch as
> > the fix.
>
> OK. I'll fix.

Done.

===================================
Subject: [Untested][RFC][PATCH] fix wrong get_user_pages usage in iovlock.c

down_read(mmap_sem)
get_user_pages()
up_read(mmap_sem)

is fork unsafe.
fix it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Maciej Sosnowski <maciej.sosnowski@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Leech <christopher.leech@intel.com>
Cc: netdev@vger.kernel.org
---
drivers/dma/iovlock.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

Index: b/drivers/dma/iovlock.c
===================================================================
--- a/drivers/dma/iovlock.c 2009-04-13 22:58:36.000000000 +0900
+++ b/drivers/dma/iovlock.c 2009-04-14 20:27:16.000000000 +0900
@@ -104,8 +104,6 @@ struct dma_pinned_list *dma_pin_iovec_pa
0, /* force */
page_list->pages,
NULL);
- up_read(&current->mm->mmap_sem);
-
if (ret != page_list->nr_pages)
goto unpin;

@@ -127,6 +125,8 @@ void dma_unpin_iovec_pages(struct dma_pi
if (!pinned_list)
return;

+ up_read(&current->mm->mmap_sem);
+
for (i = 0; i < pinned_list->nr_iovecs; i++) {
struct dma_page_list *page_list = &pinned_list->page_list[i];
for (j = 0; j < page_list->nr_pages; j++) {