Eric Lee / smarc-ti-linux-kernel

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Commit bce2a13e79891e11ebaed87ac2b68fef643426b2

Authored by Jesse Gross
Committed by Greg Kroah-Hartman
1 parent 4378fe7d79

geneve: Fix races between socket add and release. 

[ Upstream commit 12069401d895ff84076a50189ca842c0696b84b2 ]

Currently, searching for a socket to add a reference to is not
synchronized with deletion of sockets. This can result in use
after free if there is another operation that is removing a
socket at the same time. Solving this requires both holding the
appropriate lock and checking the refcount to ensure that it
has not already hit zero.

Inspired by a related (but not exactly the same) issue in the
VXLAN driver.

Fixes: 0b5e8b8e ("net: Add Geneve tunneling protocol driver")
CC: Andy Zhou <azhou@nicira.com>
Signed-off-by: Jesse Gross <jesse@nicira.com>
Acked-by: Thomas Graf <tgraf@suug.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Showing 1 changed file with 7 additions and 6 deletions Side-by-side Diff

... ... @@ -302,6 +302,7 @@
302 302 geneve_rcv_t *rcv, void *data,
303 303 bool no_share, bool ipv6)
304 304 {
  305 + struct geneve_net *gn = net_generic(net, geneve_net_id);
305 306 struct geneve_sock *gs;
306 307  
307 308 gs = geneve_socket_create(net, port, rcv, data, ipv6);
308 309  
309 310  
310 311  
... ... @@ -311,15 +312,15 @@
311 312 if (no_share) /* Return error if sharing is not allowed. */
312 313 return ERR_PTR(-EINVAL);
313 314  
  315 + spin_lock(&gn->sock_lock);
314 316 gs = geneve_find_sock(net, port);
315   - if (gs) {
316   - if (gs->rcv == rcv)
317   - atomic_inc(&gs->refcnt);
318   - else
  317 + if (gs && ((gs->rcv != rcv) ||
  318 + !atomic_add_unless(&gs->refcnt, 1, 0)))
319 319 gs = ERR_PTR(-EBUSY);
320   - } else {
  320 + spin_unlock(&gn->sock_lock);
  321 +
  322 + if (!gs)
321 323 gs = ERR_PTR(-EINVAL);
322   - }
323 324  
324 325 return gs;
325 326 }