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cifs: fix credits leak for SMB1 oplock breaks

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For SMB1 oplock breaks we would grab one credit while sending the PDU
but we would never relese the credit back since we will never receive a
response to this from the server. Eventuallt this would lead to a hang
once all credits are leaked.

Fix this by defining a new flag CIFS_NO_SRV_RSP which indicates that there
is no server response to this command and thus we need to add any credits back
immediately after sending the PDU.

CC: Stable <stable@vger.kernel.org> #v5.0+
Signed-off-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Ronnie Sahlberg 2019-05-01 12:03:41 +10:00 committed by Steve French
parent edf3ef3707
commit d69cb728e7
3 changed files with 7 additions and 6 deletions
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1
fs/cifs/cifsglob.h
View File

@ -1703,6 +1703,7 @@ static inline bool is_retryable_error(int error)
#define CIFS_HAS_CREDITS 0x0400 /* already has credits */
#define CIFS_TRANSFORM_REQ 0x0800 /* transform request before sending */
#define CIFS_NO_SRV_RSP 0x1000 /* there is no server response */
/* Security Flags: indicate type of session setup needed */
#define CIFSSEC_MAY_SIGN 0x00001

2
fs/cifs/cifssmb.c
View File

@ -2540,7 +2540,7 @@ CIFSSMBLock(const unsigned int xid, struct cifs_tcon *tcon,
if (lockType == LOCKING_ANDX_OPLOCK_RELEASE) {
/* no response expected */
flags = CIFS_ASYNC_OP | CIFS_OBREAK_OP;
flags = CIFS_NO_SRV_RSP | CIFS_ASYNC_OP | CIFS_OBREAK_OP;
pSMB->Timeout = 0;
} else if (waitFlag) {
flags = CIFS_BLOCKING_OP; /* blocking operation, no timeout */

10
fs/cifs/transport.c
View File

@ -1073,8 +1073,11 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
mutex_unlock(&ses->server->srv_mutex);
if (rc < 0) {
/* Sending failed for some reason - return credits back */
/*
* If sending failed for some reason or it is an oplock break that we
* will not receive a response to - return credits back
*/
if (rc < 0 || (flags & CIFS_NO_SRV_RSP)) {
for (i = 0; i < num_rqst; i++)
add_credits(ses->server, &credits[i], optype);
goto out;
@ -1095,9 +1098,6 @@ compound_send_recv(const unsigned int xid, struct cifs_ses *ses,
smb311_update_preauth_hash(ses, rqst[0].rq_iov,
rqst[0].rq_nvec);
if ((flags & CIFS_TIMEOUT_MASK) == CIFS_ASYNC_OP)
goto out;
for (i = 0; i < num_rqst; i++) {
rc = wait_for_response(ses->server, midQ[i]);
if (rc != 0)