From 2cffcebe17439fab6d2d54d754054cd3da547f09 Mon Sep 17 00:00:00 2001 From: Pavel Shilovsky Date: Fri, 18 Jan 2019 17:25:36 -0800 Subject: CIFS: Do not reconnect TCP session in add_credits() commit ef68e831840c40c7d01b328b3c0f5d8c4796c232 upstream. When executing add_credits() we currently call cifs_reconnect() if the number of credits is zero and there are no requests in flight. In this case we may call cifs_reconnect() recursively twice and cause memory corruption given the following sequence of functions: mid1.callback() -> add_credits() -> cifs_reconnect() -> -> mid2.callback() -> add_credits() -> cifs_reconnect(). Fix this by avoiding to call cifs_reconnect() in add_credits() and checking for zero credits in the demultiplex thread. Cc: Signed-off-by: Pavel Shilovsky Reviewed-by: Ronnie Sahlberg Signed-off-by: Steve French Signed-off-by: Greg Kroah-Hartman --- fs/cifs/connect.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) (limited to 'fs/cifs/connect.c') diff --git a/fs/cifs/connect.c b/fs/cifs/connect.c index d6248137c219..000b7bfa8cf0 100644 --- a/fs/cifs/connect.c +++ b/fs/cifs/connect.c @@ -524,6 +524,21 @@ server_unresponsive(struct TCP_Server_Info *server) return false; } +static inline bool +zero_credits(struct TCP_Server_Info *server) +{ + int val; + + spin_lock(&server->req_lock); + val = server->credits + server->echo_credits + server->oplock_credits; + if (server->in_flight == 0 && val == 0) { + spin_unlock(&server->req_lock); + return true; + } + spin_unlock(&server->req_lock); + return false; +} + static int cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg) { @@ -536,6 +551,12 @@ cifs_readv_from_socket(struct TCP_Server_Info *server, struct msghdr *smb_msg) for (total_read = 0; msg_data_left(smb_msg); total_read += length) { try_to_freeze(); + /* reconnect if no credits and no requests in flight */ + if (zero_credits(server)) { + cifs_reconnect(server); + return -ECONNABORTED; + } + if (server_unresponsive(server)) return -ECONNABORTED; -- cgit v1.2.3