Commit 84a1f5b1 authored by Paulo Alcantara (SUSE)'s avatar Paulo Alcantara (SUSE) Committed by Steve French
Browse files

cifs: Fix potential softlockups while refreshing DFS cache 



We used to skip reconnects on all SMB2_IOCTL commands due to SMB3+
FSCTL_VALIDATE_NEGOTIATE_INFO - which made sense since we're still
establishing a SMB session.

However, when refresh_cache_worker() calls smb2_get_dfs_refer() and
we're under reconnect, SMB2_ioctl() will not be able to get a proper
status error (e.g. -EHOSTDOWN in case we failed to reconnect) but an
-EAGAIN from cifs_send_recv() thus looping forever in
refresh_cache_worker().

Fixes: e99c63e4 ("SMB3: Fix deadlock in validate negotiate hits reconnect")
Signed-off-by: default avatarPaulo Alcantara (SUSE) <pc@cjr.nz>
Suggested-by: default avatarAurelien Aptel <aaptel@suse.com>
Reviewed-by: default avatarAurelien Aptel <aaptel@suse.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent df3df923

fs/cifs/smb2pdu.c

+29 −12
Original line number Diff line number Diff line
@@ -252,7 +252,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) 
	if (tcon == NULL)

		return 0;



	if (smb2_command == SMB2_TREE_CONNECT || smb2_command == SMB2_IOCTL)

	if (smb2_command == SMB2_TREE_CONNECT)

		return 0;



	if (tcon->tidStatus == CifsExiting) {
@@ -426,16 +426,9 @@ fill_small_buf(__le16 smb2_command, struct cifs_tcon *tcon, void *buf, 
 * SMB information in the SMB header. If the return code is zero, this

 * function must have filled in request_buf pointer.

 */

static int

smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,

static int __smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,

				  void **request_buf, unsigned int *total_len)

{

	int rc;



	rc = smb2_reconnect(smb2_command, tcon);

	if (rc)

		return rc;



	/* BB eventually switch this to SMB2 specific small buf size */

	if (smb2_command == SMB2_SET_INFO)

		*request_buf = cifs_buf_get();
@@ -456,7 +449,31 @@ smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon, 
		cifs_stats_inc(&tcon->num_smbs_sent);

	}



	return 0;

}



static int smb2_plain_req_init(__le16 smb2_command, struct cifs_tcon *tcon,

			       void **request_buf, unsigned int *total_len)

{

	int rc;



	rc = smb2_reconnect(smb2_command, tcon);

	if (rc)

		return rc;



	return __smb2_plain_req_init(smb2_command, tcon, request_buf,

				     total_len);

}



static int smb2_ioctl_req_init(u32 opcode, struct cifs_tcon *tcon,

			       void **request_buf, unsigned int *total_len)

{

	/* Skip reconnect only for FSCTL_VALIDATE_NEGOTIATE_INFO IOCTLs */

	if (opcode == FSCTL_VALIDATE_NEGOTIATE_INFO) {

		return __smb2_plain_req_init(SMB2_IOCTL, tcon, request_buf,

					     total_len);

	}

	return smb2_plain_req_init(SMB2_IOCTL, tcon, request_buf, total_len);

}



/* For explanation of negotiate contexts see MS-SMB2 section 2.2.3.1 */
@@ -2686,7 +2703,7 @@ SMB2_ioctl_init(struct cifs_tcon *tcon, struct smb_rqst *rqst, 
	int rc;

	char *in_data_buf;



	rc = smb2_plain_req_init(SMB2_IOCTL, tcon, (void **) &req, &total_len);

	rc = smb2_ioctl_req_init(opcode, tcon, (void **) &req, &total_len);

	if (rc)

		return rc;

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