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 <bhubb...@redhat.com>
Signed-off-by: Michael S. Tsirkin <m...@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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