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authorPavel Shilovsky <pshilov@microsoft.com>2016-11-04 21:50:31 +0300
committerPavel Shilovsky <pshilov@microsoft.com>2016-12-05 23:08:33 +0300
commit53e0e11efe9289535b060a51d4cf37c25e0d0f2b (patch)
tree46d7d80876843d554ffc9ca45ef74a2ba0233dc7 /fs/cifs/connect.c
parente3d240e9d505fc67f8f8735836df97a794bbd946 (diff)
downloadlinux-53e0e11efe9289535b060a51d4cf37c25e0d0f2b.tar.xz
CIFS: Fix a possible memory corruption during reconnect
We can not unlock/lock cifs_tcp_ses_lock while walking through ses and tcon lists because it can corrupt list iterator pointers and a tcon structure can be released if we don't hold an extra reference. Fix it by moving a reconnect process to a separate delayed work and acquiring a reference to every tcon that needs to be reconnected. Also do not send an echo request on newly established connections. CC: Stable <stable@vger.kernel.org> Signed-off-by: Pavel Shilovsky <pshilov@microsoft.com>
Diffstat (limited to 'fs/cifs/connect.c')
-rw-r--r--fs/cifs/connect.c34
1 files changed, 27 insertions, 7 deletions
diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c
index 5563de3c64fd..5aaf7b1359a5 100644
--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -52,6 +52,9 @@
#include "nterr.h"
#include "rfc1002pdu.h"
#include "fscache.h"
+#ifdef CONFIG_CIFS_SMB2
+#include "smb2proto.h"
+#endif
#define CIFS_PORT 445
#define RFC1001_PORT 139
@@ -2110,8 +2113,8 @@ cifs_find_tcp_session(struct smb_vol *vol)
return NULL;
}
-static void
-cifs_put_tcp_session(struct TCP_Server_Info *server)
+void
+cifs_put_tcp_session(struct TCP_Server_Info *server, int from_reconnect)
{
struct task_struct *task;
@@ -2128,6 +2131,19 @@ cifs_put_tcp_session(struct TCP_Server_Info *server)
cancel_delayed_work_sync(&server->echo);
+#ifdef CONFIG_CIFS_SMB2
+ if (from_reconnect)
+ /*
+ * Avoid deadlock here: reconnect work calls
+ * cifs_put_tcp_session() at its end. Need to be sure
+ * that reconnect work does nothing with server pointer after
+ * that step.
+ */
+ cancel_delayed_work(&server->reconnect);
+ else
+ cancel_delayed_work_sync(&server->reconnect);
+#endif
+
spin_lock(&GlobalMid_Lock);
server->tcpStatus = CifsExiting;
spin_unlock(&GlobalMid_Lock);
@@ -2192,6 +2208,10 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);
INIT_LIST_HEAD(&tcp_ses->smb_ses_list);
INIT_DELAYED_WORK(&tcp_ses->echo, cifs_echo_request);
+#ifdef CONFIG_CIFS_SMB2
+ INIT_DELAYED_WORK(&tcp_ses->reconnect, smb2_reconnect_server);
+ mutex_init(&tcp_ses->reconnect_mutex);
+#endif
memcpy(&tcp_ses->srcaddr, &volume_info->srcaddr,
sizeof(tcp_ses->srcaddr));
memcpy(&tcp_ses->dstaddr, &volume_info->dstaddr,
@@ -2350,7 +2370,7 @@ cifs_put_smb_ses(struct cifs_ses *ses)
spin_unlock(&cifs_tcp_ses_lock);
sesInfoFree(ses);
- cifs_put_tcp_session(server);
+ cifs_put_tcp_session(server, 0);
}
#ifdef CONFIG_KEYS
@@ -2524,7 +2544,7 @@ cifs_get_smb_ses(struct TCP_Server_Info *server, struct smb_vol *volume_info)
mutex_unlock(&ses->session_mutex);
/* existing SMB ses has a server reference already */
- cifs_put_tcp_session(server);
+ cifs_put_tcp_session(server, 0);
free_xid(xid);
return ses;
}
@@ -2620,7 +2640,7 @@ cifs_find_tcon(struct cifs_ses *ses, struct smb_vol *volume_info)
return NULL;
}
-static void
+void
cifs_put_tcon(struct cifs_tcon *tcon)
{
unsigned int xid;
@@ -3824,7 +3844,7 @@ mount_fail_check:
else if (ses)
cifs_put_smb_ses(ses);
else
- cifs_put_tcp_session(server);
+ cifs_put_tcp_session(server, 0);
bdi_destroy(&cifs_sb->bdi);
}
@@ -4135,7 +4155,7 @@ cifs_construct_tcon(struct cifs_sb_info *cifs_sb, kuid_t fsuid)
ses = cifs_get_smb_ses(master_tcon->ses->server, vol_info);
if (IS_ERR(ses)) {
tcon = (struct cifs_tcon *)ses;
- cifs_put_tcp_session(master_tcon->ses->server);
+ cifs_put_tcp_session(master_tcon->ses->server, 0);
goto out;
}