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author | Paulo Alcantara <paulo@paulo.ac> | 2018-07-05 18:46:34 +0200 |
---|---|---|
committer | Steve French <stfrench@microsoft.com> | 2018-07-05 20:48:25 +0200 |
commit | 7ffbe65578b44fafdef577a360eb0583929f7c6e (patch) | |
tree | 794ee9d2c1a4dd7ae3a71248d2560785272ddfa1 /fs | |
parent | cifs: Fix slab-out-of-bounds in send_set_info() on SMB2 ACE setting (diff) | |
download | linux-7ffbe65578b44fafdef577a360eb0583929f7c6e.tar.xz linux-7ffbe65578b44fafdef577a360eb0583929f7c6e.zip |
cifs: Fix infinite loop when using hard mount option
For every request we send, whether it is SMB1 or SMB2+, we attempt to
reconnect tcon (cifs_reconnect_tcon or smb2_reconnect) before carrying
out the request.
So, while server->tcpStatus != CifsNeedReconnect, we wait for the
reconnection to succeed on wait_event_interruptible_timeout(). If it
returns, that means that either the condition was evaluated to true, or
timeout elapsed, or it was interrupted by a signal.
Since we're not handling the case where the process woke up due to a
received signal (-ERESTARTSYS), the next call to
wait_event_interruptible_timeout() will _always_ fail and we end up
looping forever inside either cifs_reconnect_tcon() or smb2_reconnect().
Here's an example of how to trigger that:
$ mount.cifs //foo/share /mnt/test -o
username=foo,password=foo,vers=1.0,hard
(break connection to server before executing bellow cmd)
$ stat -f /mnt/test & sleep 140
[1] 2511
$ ps -aux -q 2511
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 2511 0.0 0.0 12892 1008 pts/0 S 12:24 0:00 stat -f
/mnt/test
$ kill -9 2511
(wait for a while; process is stuck in the kernel)
$ ps -aux -q 2511
USER PID %CPU %MEM VSZ RSS TTY STAT START TIME COMMAND
root 2511 83.2 0.0 12892 1008 pts/0 R 12:24 30:01 stat -f
/mnt/test
By using 'hard' mount point means that cifs.ko will keep retrying
indefinitely, however we must allow the process to be killed otherwise
it would hang the system.
Signed-off-by: Paulo Alcantara <palcantara@suse.de>
Cc: stable@vger.kernel.org
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
Diffstat (limited to '')
-rw-r--r-- | fs/cifs/cifssmb.c | 10 | ||||
-rw-r--r-- | fs/cifs/smb2pdu.c | 18 |
2 files changed, 20 insertions, 8 deletions
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c index d352da325de3..93408eab92e7 100644 --- a/fs/cifs/cifssmb.c +++ b/fs/cifs/cifssmb.c @@ -157,8 +157,14 @@ cifs_reconnect_tcon(struct cifs_tcon *tcon, int smb_command) * greater than cifs socket timeout which is 7 seconds */ while (server->tcpStatus == CifsNeedReconnect) { - wait_event_interruptible_timeout(server->response_q, - (server->tcpStatus != CifsNeedReconnect), 10 * HZ); + rc = wait_event_interruptible_timeout(server->response_q, + (server->tcpStatus != CifsNeedReconnect), + 10 * HZ); + if (rc < 0) { + cifs_dbg(FYI, "%s: aborting reconnect due to a received" + " signal by the process\n", __func__); + return -ERESTARTSYS; + } /* are we still trying to reconnect? */ if (server->tcpStatus != CifsNeedReconnect) diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index dbfb83ae6137..e31375ecaa6f 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -155,7 +155,7 @@ out: static int smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) { - int rc = 0; + int rc; struct nls_table *nls_codepage; struct cifs_ses *ses; struct TCP_Server_Info *server; @@ -166,10 +166,10 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) * for those three - in the calling routine. */ if (tcon == NULL) - return rc; + return 0; if (smb2_command == SMB2_TREE_CONNECT) - return rc; + return 0; if (tcon->tidStatus == CifsExiting) { /* @@ -212,8 +212,14 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) return -EAGAIN; } - wait_event_interruptible_timeout(server->response_q, - (server->tcpStatus != CifsNeedReconnect), 10 * HZ); + rc = wait_event_interruptible_timeout(server->response_q, + (server->tcpStatus != CifsNeedReconnect), + 10 * HZ); + if (rc < 0) { + cifs_dbg(FYI, "%s: aborting reconnect due to a received" + " signal by the process\n", __func__); + return -ERESTARTSYS; + } /* are we still trying to reconnect? */ if (server->tcpStatus != CifsNeedReconnect) @@ -231,7 +237,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon) } if (!tcon->ses->need_reconnect && !tcon->need_reconnect) - return rc; + return 0; nls_codepage = load_nls_default(); |