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authorPaulo Alcantara <paulo@paulo.ac>2018-07-05 13:46:34 -0300
committerSteve French <stfrench@microsoft.com>2018-07-05 13:48:25 -0500
commit7ffbe65578b44fafdef577a360eb0583929f7c6e (patch)
tree794ee9d2c1a4dd7ae3a71248d2560785272ddfa1
parentf46ecbd97f508e68a7806291a139499794874f3d (diff)
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>
-rw-r--r--fs/cifs/cifssmb.c10
-rw-r--r--fs/cifs/smb2pdu.c18
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();