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tun: fix recovery from gup errors 

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>
Acked-by: Jason Wang <jasowang@redhat.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Michael S. Tsirkin 2013-06-23 17:19:03 +03:00 committed by David S. Miller
parent bd8a7036c0
commit 7e24bfbe43
1 changed files with 4 additions and 2 deletions
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6
drivers/net/tun.c
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@ -1010,8 +1010,10 @@ 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;