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cifs: fix dentry refcount leak when opening a FIFO on lookup 

The cifs code will attempt to open files on lookup under certain
circumstances. What happens though if we find that the file we opened
was actually a FIFO or other special file?

Currently, the open filehandle just ends up being leaked leading to
a dentry refcount mismatch and oops on umount. Fix this by having the
code close the filehandle on the server if it turns out not to be a
regular file. While we're at it, change this spaghetti if statement
into a switch too.

Cc: stable@vger.kernel.org
Reported-by: CAI Qian <caiqian@redhat.com>
Tested-by: CAI Qian <caiqian@redhat.com>
Reviewed-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
This commit is contained in:
Jeff Layton 2012-02-23 09:37:45 -05:00 committed by Steve French
parent 6de2ce4231
commit 5bccda0ebc
1 changed files with 18 additions and 2 deletions
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20
fs/cifs/dir.c
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@ -584,10 +584,26 @@ cifs_lookup(struct inode *parent_dir_inode, struct dentry *direntry,
* If either that or op not supported returned, follow
* the normal lookup.
*/
if ((rc == 0) || (rc == -ENOENT))
switch (rc) {
case 0:
/*
* The server may allow us to open things like
* FIFOs, but the client isn't set up to deal
* with that. If it's not a regular file, just
* close it and proceed as if it were a normal
* lookup.
*/
if (newInode && !S_ISREG(newInode->i_mode)) {
CIFSSMBClose(xid, pTcon, fileHandle);
break;
}
case -ENOENT:
posix_open = true;
else if ((rc == -EINVAL) || (rc != -EOPNOTSUPP))
case -EOPNOTSUPP:
break;
default:
pTcon->broken_posix_open = true;
}
}
if (!posix_open)
rc = cifs_get_inode_info_unix(&newInode, full_path,