sock: fix zerocopy panic in mem accounting
Only call mm_unaccount_pinned_pages when releasing a struct ubuf_info
that has initialized its field uarg->mmp.
Before this patch, a vhost-net with experimental_zcopytx can crash in
mm_unaccount_pinned_pages
sock_zerocopy_put
skb_zcopy_clear
skb_release_data
Only sock_zerocopy_alloc initializes this field. Move the unaccount
call from generic sock_zerocopy_put to its specific callback
sock_zerocopy_callback.
Fixes: a91dbff551a6 ("sock: ulimit on MSG_ZEROCOPY pages")
Reported-by: David Ahern <dsahern@gmail.com>
Signed-off-by: Willem de Bruijn <willemb@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 42b62c71..cb12359 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -1044,6 +1044,8 @@ void sock_zerocopy_callback(struct ubuf_info *uarg, bool success)
u32 lo, hi;
u16 len;
+ mm_unaccount_pinned_pages(&uarg->mmp);
+
/* if !len, there was only 1 call, and it was aborted
* so do not queue a completion notification
*/
@@ -1084,8 +1086,6 @@ EXPORT_SYMBOL_GPL(sock_zerocopy_callback);
void sock_zerocopy_put(struct ubuf_info *uarg)
{
if (uarg && atomic_dec_and_test(&uarg->refcnt)) {
- mm_unaccount_pinned_pages(&uarg->mmp);
-
if (uarg->callback)
uarg->callback(uarg, uarg->zerocopy);
else