| From | Ben Hutchings <> | Date | Wed, 31 Jul 2013 15:23:09 +0200 | Subject | [03/84] macvtap: fix recovery from gup errors |
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3.2.50-rc1 review patch. If anyone has any objections, please let me know.
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From: "Michael S. Tsirkin" <mst@redhat.com>
[ Upstream commit 4c7ab054ab4f5d63625508ed6f8a607184cae7c2 ]
get user pages might fail partially in macvtap 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> Acked-by: Jason Wang <jasowang@redhat.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- drivers/net/macvtap.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c index 26106c0..d91858e 100644 --- a/drivers/net/macvtap.c +++ b/drivers/net/macvtap.c @@ -532,8 +532,10 @@ 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;
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