6.15-stable review patch. If anyone has any objections, please let me know.
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From: Shyam Prasad N sprasad@microsoft.com
commit b5e3e6e28cf3853566ba5d816f79aba5be579158 upstream.
Today, during smb2_reconnect, session_mutex is released as soon as the tcon is reconnected and is in a good state. However, in case multichannel is enabled, there is also a query of server interfaces that follows. We've seen that this query can race with reconnects of other channels, causing them to step on each other with reconnects.
This change extends the hold of session_mutex till after the query of server interfaces is complete. In order to avoid recursive smb2_reconnect checks during query ioctl, this change also introduces a session flag for sessions where such a query is in progress.
Signed-off-by: Shyam Prasad N sprasad@microsoft.com Cc: stable@vger.kernel.org Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- fs/smb/client/cifsglob.h | 1 + fs/smb/client/smb2pdu.c | 24 ++++++++++++++++++------ 2 files changed, 19 insertions(+), 6 deletions(-)
--- a/fs/smb/client/cifsglob.h +++ b/fs/smb/client/cifsglob.h @@ -1084,6 +1084,7 @@ struct cifs_chan { };
#define CIFS_SES_FLAG_SCALE_CHANNELS (0x1) +#define CIFS_SES_FLAGS_PENDING_QUERY_INTERFACES (0x2)
/* * Session structure. One of these for each uid session with a particular host --- a/fs/smb/client/smb2pdu.c +++ b/fs/smb/client/smb2pdu.c @@ -411,14 +411,19 @@ skip_sess_setup: if (!rc && (server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL) && server->ops->query_server_interfaces) { - mutex_unlock(&ses->session_mutex); - /* - * query server network interfaces, in case they change + * query server network interfaces, in case they change. + * Also mark the session as pending this update while the query + * is in progress. This will be used to avoid calling + * smb2_reconnect recursively. */ + ses->flags |= CIFS_SES_FLAGS_PENDING_QUERY_INTERFACES; xid = get_xid(); rc = server->ops->query_server_interfaces(xid, tcon, false); free_xid(xid); + ses->flags &= ~CIFS_SES_FLAGS_PENDING_QUERY_INTERFACES; + + mutex_unlock(&ses->session_mutex);
if (rc == -EOPNOTSUPP && ses->chan_count > 1) { /* @@ -560,11 +565,18 @@ static int smb2_ioctl_req_init(u32 opcod struct TCP_Server_Info *server, void **request_buf, unsigned int *total_len) { - /* Skip reconnect only for FSCTL_VALIDATE_NEGOTIATE_INFO IOCTLs */ - if (opcode == FSCTL_VALIDATE_NEGOTIATE_INFO) { + /* + * Skip reconnect in one of the following cases: + * 1. For FSCTL_VALIDATE_NEGOTIATE_INFO IOCTLs + * 2. For FSCTL_QUERY_NETWORK_INTERFACE_INFO IOCTL when called from + * smb2_reconnect (indicated by CIFS_SES_FLAG_SCALE_CHANNELS ses flag) + */ + if (opcode == FSCTL_VALIDATE_NEGOTIATE_INFO || + (opcode == FSCTL_QUERY_NETWORK_INTERFACE_INFO && + (tcon->ses->flags & CIFS_SES_FLAGS_PENDING_QUERY_INTERFACES))) return __smb2_plain_req_init(SMB2_IOCTL, tcon, server, request_buf, total_len); - } + return smb2_plain_req_init(SMB2_IOCTL, tcon, server, request_buf, total_len); }