Serialise access of TCP_Server_Info::hostname in
assemble_neg_contexts() by holding the server's mutex otherwise it
might end up accessing an already-freed hostname pointer from
cifs_reconnect() or cifs_resolve_server().
Signed-off-by: Paulo Alcantara (SUSE) <pc@xxxxxx>
---
fs/cifs/smb2pdu.c | 11 +++++++----
1 file changed, 7 insertions(+), 4 deletions(-)
diff --git a/fs/cifs/smb2pdu.c b/fs/cifs/smb2pdu.c
index a5695748a89b..2c484d47c592 100644
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -541,9 +541,10 @@ static void
assemble_neg_contexts(struct smb2_negotiate_req *req,
struct TCP_Server_Info *server, unsigned int *total_len)
{
- char *pneg_ctxt;
- char *hostname = NULL;
unsigned int ctxt_len, neg_context_count;
+ struct TCP_Server_Info *pserver;
+ char *pneg_ctxt;
+ char *hostname;
if (*total_len > 200) {
/* In case length corrupted don't want to overrun smb buffer */
@@ -574,8 +575,9 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
* secondary channels don't have the hostname field populated
* use the hostname field in the primary channel instead
*/
- hostname = CIFS_SERVER_IS_CHAN(server) ?
- server->primary_server->hostname : server->hostname;
+ pserver = CIFS_SERVER_IS_CHAN(server) ? server->primary_server : server;
+ cifs_server_lock(pserver);
+ hostname = pserver->hostname;
if (hostname && (hostname[0] != 0)) {
ctxt_len = build_netname_ctxt((struct smb2_netname_neg_context *)pneg_ctxt,
hostname);
@@ -584,6 +586,7 @@ assemble_neg_contexts(struct smb2_negotiate_req *req,
neg_context_count = 3;
} else
neg_context_count = 2;
+ cifs_server_unlock(pserver);
build_posix_ctxt((struct smb2_posix_neg_context *)pneg_ctxt);
*total_len += sizeof(struct smb2_posix_neg_context);
--
2.39.0
