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cifs: fix kref underflow in close_shroot() 

Fix a bug where we used to not initialize the cached fid structure at all
in open_shroot() if the open was successful but we did not get a lease.
This would leave the structure uninitialized and later when we close the handle
we would in close_shroot() try to kref_put() an uninitialized refcount.

Fix this by always initializing this structure if the open was successful
but only do the extra get() if we got a lease.
This extra get() is only used to hold the structure until we get a lease
break from the server at which point we will kref_put() it during lease
processing.

Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
CC: Stable <stable@vger.kernel.org>
This commit is contained in:
Ronnie Sahlberg 2019-03-28 11:20:02 +10:00 committed by Steve French
parent 5e7a8ca319
commit 2f94a3125b
1 changed files with 7 additions and 9 deletions
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16
fs/cifs/smb2ops.c
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@ -717,20 +717,18 @@ int open_shroot(unsigned int xid, struct cifs_tcon *tcon, struct cifs_fid *pfid)
oparms.fid->mid = le64_to_cpu(o_rsp->sync_hdr.MessageId);
#endif /* CIFS_DEBUG2 */
if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE)
oplock = smb2_parse_lease_state(server, o_rsp,
&oparms.fid->epoch,
oparms.fid->lease_key);
else
goto oshr_exit;
memcpy(tcon->crfid.fid, pfid, sizeof(struct cifs_fid));
tcon->crfid.tcon = tcon;
tcon->crfid.is_valid = true;
kref_init(&tcon->crfid.refcount);
kref_get(&tcon->crfid.refcount);
if (o_rsp->OplockLevel == SMB2_OPLOCK_LEVEL_LEASE) {
kref_get(&tcon->crfid.refcount);
oplock = smb2_parse_lease_state(server, o_rsp,
&oparms.fid->epoch,
oparms.fid->lease_key);
} else
goto oshr_exit;
qi_rsp = (struct smb2_query_info_rsp *)rsp_iov[1].iov_base;
if (le32_to_cpu(qi_rsp->OutputBufferLength) < sizeof(struct smb2_file_all_info))