Messages in this thread Patch in this message | | | Date | Sun, 23 Jun 2013 17:19:03 +0300 | From | "Michael S. Tsirkin" <> | Subject | [PATCH net] tun: fix recovery from gup errors |
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get user pages might fail partially in tun zero copy mode. To recover we need to put all pages that we got, but code used a wrong index resulting in double-free errors.
Reported-by: Brad Hubbard <bhubbard@redhat.com> Signed-off-by: Michael S. Tsirkin <mst@redhat.com> ---
I haven't figured out why do we get failures, but recovery is clearly wrong.
This is also -stable material.
drivers/net/tun.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-)
diff --git a/drivers/net/tun.c b/drivers/net/tun.c index bfa9bb4..c098b1e 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -1010,8 +1010,9 @@ static int zerocopy_sg_from_iovec(struct sk_buff *skb, const struct iovec *from, return -EMSGSIZE; num_pages = get_user_pages_fast(base, size, 0, &page[i]); if (num_pages != size) { - for (i = 0; i < num_pages; i++) - put_page(page[i]); + int j; + for (j = 0; j < num_pages; j++) + put_page(page[i + j]); return -EFAULT; } truesize = size * PAGE_SIZE; -- MST
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