[bug report] crypto: chtls - Register chtls with net tls

[Dan Carpenter]

Hello Atul Gupta,

The patch a08943947873: "crypto: chtls - Register chtls with net tls"
from Mar 31, 2018, leads to the following static checker warning:

        drivers/crypto/chelsio/chtls/chtls_main.c:352 chtls_recv_packet()
        error: double free of 'skb'

drivers/crypto/chelsio/chtls/chtls_main.c
   337  static int chtls_recv_packet(struct chtls_dev *cdev,
   338                               const struct pkt_gl *gl, const __be64 *rsp)
   339  {
   340          unsigned int opcode = *(u8 *)rsp;
   341          struct sk_buff *skb;
   342          int ret;
   343  
   344          skb = copy_gl_to_skb_pkt(gl, rsp, cdev->lldi->sge_pktshift);
   345          if (!skb)
   346                  return -ENOMEM;
   347  
   348          ret = chtls_handlers[opcode](cdev, skb);
   349          if (ret & CPL_RET_BUF_DONE)
   350                  kfree_skb(skb);

This is a false positive because Smatch doesn't parse the test for
CPL_RET_BUF_DONE set correctly.  It's not that complicated for me to fix
that in Smatch so I will eventually.  But really this is risky code.
A bunch of these handler functions return -EINVAL.  If they return an
odd numbered error code instead then we free skb which is pretty
subtle so far as APIs are concerned.

Looking at it now, I think we probably should be freeing skb on those
paths.  The current code looks leaky to me.

   351  
   352          return 0;
   353  }

regards,
dan carpenter