Commit 74c2ab6d authored by Su Hui's avatar Su Hui Committed by Steve French
Browse files

smb/client: avoid possible NULL dereference in cifs_free_subrequest() 



Clang static checker (scan-build) warning:
	cifsglob.h:line 890, column 3
	Access to field 'ops' results in a dereference of a null pointer.

Commit 519be989 ("cifs: Add a tracepoint to track credits involved in
R/W requests") adds a check for 'rdata->server', and let clang throw this
warning about NULL dereference.

When 'rdata->credits.value != 0 && rdata->server == NULL' happens,
add_credits_and_wake_if() will call rdata->server->ops->add_credits().
This will cause NULL dereference problem. Add a check for 'rdata->server'
to avoid NULL dereference.

Cc: stable@vger.kernel.org
Fixes: 69c3c023 ("cifs: Implement netfslib hooks")
Reviewed-by: default avatarDavid Howells <dhowells@redhat.com>
Signed-off-by: default avatarSu Hui <suhui@nfschina.com>
Signed-off-by: default avatarSteve French <stfrench@microsoft.com>
parent 7c626ce4

fs/smb/client/file.c

+6 −2
Original line number Diff line number Diff line
@@ -315,7 +315,7 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq) 
#endif

	}



	if (rdata->credits.value != 0)

	if (rdata->credits.value != 0) {

		trace_smb3_rw_credits(rdata->rreq->debug_id,

				      rdata->subreq.debug_index,

				      rdata->credits.value,
@@ -323,8 +323,12 @@ static void cifs_free_subrequest(struct netfs_io_subrequest *subreq) 
				      rdata->server ? rdata->server->in_flight : 0,

				      -rdata->credits.value,

				      cifs_trace_rw_credits_free_subreq);



		if (rdata->server)

			add_credits_and_wake_if(rdata->server, &rdata->credits, 0);

		else

			rdata->credits.value = 0;

	}



	if (rdata->have_xid)

		free_xid(rdata->xid);

}