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cifs: prevent infinite recursion in cifs_reconnect_tcon

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cifs_reconnect_tcon is called from smb_init. After a successful
reconnect, cifs_reconnect_tcon will call reset_cifs_unix_caps. That
function will, in turn call CIFSSMBQFSUnixInfo and CIFSSMBSetFSUnixInfo.
Those functions also call smb_init.

It's possible for the session and tcon reconnect to succeed, and then
for another cifs_reconnect to occur before CIFSSMBQFSUnixInfo or
CIFSSMBSetFSUnixInfo to be called. That'll cause those functions to call
smb_init and cifs_reconnect_tcon again, ad infinitum...

Break the infinite recursion by having those functions use a new
smb_init variant that doesn't attempt to perform a reconnect.

Reported-and-Tested-by: Michal Suchanek <hramrach@centrum.cz>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <sfrench@us.ibm.com>
This commit is contained in:
Jeff Layton 2010-09-29 15:27:08 -04:00 committed by Steve French
parent 522440ed55
commit f569599ae7
1 changed files with 33 additions and 16 deletions
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47
fs/cifs/cifssmb.c
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@ -232,7 +232,7 @@ static int
small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
void **request_buf) void **request_buf)
{ {
int rc = 0; int rc;
rc = cifs_reconnect_tcon(tcon, smb_command); rc = cifs_reconnect_tcon(tcon, smb_command);
if (rc) if (rc)
@ -250,7 +250,7 @@ small_smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
if (tcon != NULL) if (tcon != NULL)
cifs_stats_inc(&tcon->num_smbs_sent); cifs_stats_inc(&tcon->num_smbs_sent);
return rc; return 0;
} }
int int
@ -281,16 +281,9 @@ small_smb_init_no_tc(const int smb_command, const int wct,
/* If the return code is zero, this function must fill in request_buf pointer */ /* If the return code is zero, this function must fill in request_buf pointer */
static int static int
smb_init(int smb_command, int wct, struct cifsTconInfo *tcon, __smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
void **request_buf /* returned */ , void **request_buf, void **response_buf)
void **response_buf /* returned */ )
{ {
int rc = 0;
rc = cifs_reconnect_tcon(tcon, smb_command);
if (rc)
return rc;
*request_buf = cifs_buf_get(); *request_buf = cifs_buf_get();
if (*request_buf == NULL) { if (*request_buf == NULL) {
/* BB should we add a retry in here if not a writepage? */ /* BB should we add a retry in here if not a writepage? */
@ -309,7 +302,31 @@ smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
if (tcon != NULL) if (tcon != NULL)
cifs_stats_inc(&tcon->num_smbs_sent); cifs_stats_inc(&tcon->num_smbs_sent);
return 0;
}
/* If the return code is zero, this function must fill in request_buf pointer */
static int
smb_init(int smb_command, int wct, struct cifsTconInfo *tcon,
void **request_buf, void **response_buf)
{
int rc;
rc = cifs_reconnect_tcon(tcon, smb_command);
if (rc)
return rc; return rc;
return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
}
static int
smb_init_no_reconnect(int smb_command, int wct, struct cifsTconInfo *tcon,
void **request_buf, void **response_buf)
{
if (tcon->ses->need_reconnect || tcon->need_reconnect)
return -EHOSTDOWN;
return __smb_init(smb_command, wct, tcon, request_buf, response_buf);
} }
static int validate_t2(struct smb_t2_rsp *pSMB) static int validate_t2(struct smb_t2_rsp *pSMB)
@ -4534,8 +4551,8 @@ CIFSSMBQFSUnixInfo(const int xid, struct cifsTconInfo *tcon)
cFYI(1, "In QFSUnixInfo"); cFYI(1, "In QFSUnixInfo");
QFSUnixRetry: QFSUnixRetry:
rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB, rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
(void **) &pSMBr); (void **) &pSMB, (void **) &pSMBr);
if (rc) if (rc)
return rc; return rc;
@ -4604,8 +4621,8 @@ CIFSSMBSetFSUnixInfo(const int xid, struct cifsTconInfo *tcon, __u64 cap)
cFYI(1, "In SETFSUnixInfo"); cFYI(1, "In SETFSUnixInfo");
SETFSUnixRetry: SETFSUnixRetry:
/* BB switch to small buf init to save memory */ /* BB switch to small buf init to save memory */
rc = smb_init(SMB_COM_TRANSACTION2, 15, tcon, (void **) &pSMB, rc = smb_init_no_reconnect(SMB_COM_TRANSACTION2, 15, tcon,
(void **) &pSMBr); (void **) &pSMB, (void **) &pSMBr);
if (rc) if (rc)
return rc; return rc;