From 5fb4e288a025af1abc5c67ecebf30fbf6b3edad1 Mon Sep 17 00:00:00 2001 From: Christopher Oo Date: Thu, 25 Jun 2015 16:10:48 -0700 Subject: cifs: Fix use-after-free on mid_q_entry With CIFS_DEBUG_2 enabled, additional debug information is tracked inside each mid_q_entry struct, however cifs_save_when_sent may use the mid_q_entry after it has been freed from the appropriate callback if the transport layer has very low latency. Holding the srv_mutex fixes this use-after-free, as cifs_save_when_sent is called while the srv_mutex is held while the request is sent. Signed-off-by: Christopher Oo --- fs/cifs/smb2pdu.c | 7 +++++++ 1 file changed, 7 insertions(+) (limited to 'fs/cifs/smb2pdu.c') diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c index b8b4f08ee094..070fb2ad85ce 100644 --- a/fs/cifs/smb2pdu.c +++ b/fs/cifs/smb2pdu.c @@ -1626,7 +1626,9 @@ smb2_echo_callback(struct mid_q_entry *mid) if (mid->mid_state == MID_RESPONSE_RECEIVED) credits_received = le16_to_cpu(smb2->hdr.CreditRequest); + mutex_lock(&server->srv_mutex); DeleteMidQEntry(mid); + mutex_unlock(&server->srv_mutex); add_credits(server, credits_received, CIFS_ECHO_OP); } @@ -1810,7 +1812,9 @@ smb2_readv_callback(struct mid_q_entry *mid) cifs_stats_fail_inc(tcon, SMB2_READ_HE); queue_work(cifsiod_wq, &rdata->work); + mutex_lock(&server->srv_mutex); DeleteMidQEntry(mid); + mutex_unlock(&server->srv_mutex); add_credits(server, credits_received, 0); } @@ -1938,6 +1942,7 @@ smb2_writev_callback(struct mid_q_entry *mid) { struct cifs_writedata *wdata = mid->callback_data; struct cifs_tcon *tcon = tlink_tcon(wdata->cfile->tlink); + struct TCP_Server_Info *server = tcon->ses->server; unsigned int written; struct smb2_write_rsp *rsp = (struct smb2_write_rsp *)mid->resp_buf; unsigned int credits_received = 1; @@ -1977,7 +1982,9 @@ smb2_writev_callback(struct mid_q_entry *mid) cifs_stats_fail_inc(tcon, SMB2_WRITE_HE); queue_work(cifsiod_wq, &wdata->work); + mutex_lock(&server->srv_mutex); DeleteMidQEntry(mid); + mutex_unlock(&server->srv_mutex); add_credits(tcon->ses->server, credits_received, 0); } -- cgit