From: Paulo Alcantara pc@cjr.nz
[ Upstream commit 775e44d6d86dca400d614cbda5dab4def4951fe7 ]
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@cjr.nz Reviewed-by: Enzo Matsumiya ematsumiya@suse.de Signed-off-by: Steve French stfrench@microsoft.com Signed-off-by: Sasha Levin sashal@kernel.org --- 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 4ac5b1bfaf78..727f16b426be 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);