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cifs: avoid races in parallel reconnects in smb1

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Prevent multiple threads of doing negotiate, session setup and tree
connect by holding @ses->session_mutex in cifs_reconnect_tcon() while
reconnecting session and tcon.

Signed-off-by: Paulo Alcantara (SUSE) <pc@manguebit.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
This commit is contained in:
Paulo Alcantara 2023-03-29 17:14:21 -03:00 committed by Steve French
parent 179a88a855
commit 6cc041e90c
1 changed files with 15 additions and 6 deletions
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21
fs/cifs/cifssmb.c
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@ -71,7 +71,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
int rc;
struct cifs_ses *ses;
struct TCP_Server_Info *server;
struct nls_table *nls_codepage;
struct nls_table *nls_codepage = NULL;
/*
* SMBs NegProt, SessSetup, uLogoff do not have tcon yet so check for
@ -99,6 +99,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
}
spin_unlock(&tcon->tc_lock);
again:
rc = cifs_wait_for_server_reconnect(server, tcon->retry);
if (rc)
return rc;
@ -110,8 +111,7 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
}
spin_unlock(&ses->chan_lock);
nls_codepage = load_nls_default();
mutex_lock(&ses->session_mutex);
/*
* Recheck after acquire mutex. If another thread is negotiating
* and the server never sends an answer the socket will be closed
@ -120,29 +120,38 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command)
spin_lock(&server->srv_lock);
if (server->tcpStatus == CifsNeedReconnect) {
spin_unlock(&server->srv_lock);
mutex_lock(&ses->session_mutex);
if (tcon->retry)
goto again;
rc = -EHOSTDOWN;
goto out;
}
spin_unlock(&server->srv_lock);
nls_codepage = load_nls_default();
/*
* need to prevent multiple threads trying to simultaneously
* reconnect the same SMB session
*/
spin_lock(&ses->ses_lock);
spin_lock(&ses->chan_lock);
if (!cifs_chan_needs_reconnect(ses, server)) {
if (!cifs_chan_needs_reconnect(ses, server) &&
ses->ses_status == SES_GOOD) {
spin_unlock(&ses->chan_lock);
spin_unlock(&ses->ses_lock);
/* this means that we only need to tree connect */
if (tcon->need_reconnect)
goto skip_sess_setup;
rc = -EHOSTDOWN;
mutex_unlock(&ses->session_mutex);
goto out;
}
spin_unlock(&ses->chan_lock);
spin_unlock(&ses->ses_lock);
mutex_lock(&ses->session_mutex);
rc = cifs_negotiate_protocol(0, ses, server);
if (!rc)
rc = cifs_setup_session(0, ses, server, nls_codepage);