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Date: Thu, 30 Jun 2011 07:51:56 -0400
From: Jim Rees <rees@umich.edu>
To: faizan husain <faizanh@linux.vnet.ibm.com>
Cc: linux-nfs@vger.kernel.org, Frank S Filz <ffilz@us.ibm.com>,
        jvrao@linux.vnet.ibm.com
Subject: Re: [PATCH] nfs4-acl-tools : nfs4_setfacl' failed with unexpected
 messages if the format of the input file is incorrect.
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faizan husain wrote:

  problem was this part of code in parse_alloc_fields() function:
  if (count != 3)
           goto out_free;
  at this point memory is not allocated for fields leading to double
  free of memory once inside parse_alloc_fields() and again inside
  nfs4_ace_from_string().
  
  instead we can change the  code:
  if (count != 3)
      return -EINVAL; /*Invalid argument*/
  
  This look to me as more foolproof solution.
  what do you say?

That looks correct.  It should return EINVAL here, and there is no need to
free.  But I don't see why it fixes your segfault.  fields[] should be all
NULL at this point, so free_fields shouldn't do anything.

The test in free_fields() is redundant, since free(NULL) doesn't do
anything.  But it could be made more foolproof by zeroing the array so you
can't get a double free:

void
free_fields(char *fields[NUMFIELDS])
{
	int i;

	for (i = 0; i < NUMFIELDS; i++) {
		free(fields[i]);
		fields[i] = NULL;
	}
}