selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 50 insertions, 0 deletions

diff --git a/fs/smb/client/compress.h b/fs/smb/client/compress.h
new file mode 100644
index 000000000..e08e6d339
--- /dev/null
+++ b/fs/smb/client/compress.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright (C) 2024, SUSE LLC
+ *
+ * Authors: Enzo Matsumiya <ematsumiya@suse.de>
+ *
+ * This file implements I/O compression support for SMB2 messages (SMB 3.1.1 only).
+ * See compress/ for implementation details of each algorithm.
+ *
+ * References:
+ * MS-SMB2 "3.1.4.4 Compressing the Message" - for compression details
+ * MS-SMB2 "3.1.5.3 Decompressing the Chained Message" - for decompression details
+ * MS-XCA - for details of the supported algorithms
+ */
+#ifndef _SMB_COMPRESS_H
+#define _SMB_COMPRESS_H
+
+#include <linux/uio.h>
+#include <linux/kernel.h>
+#include "../common/smb2pdu.h"
+#include "../common/compress/compress.h"
+#include "cifsglob.h"
+
+/* sizeof(smb2_compression_hdr) - sizeof(OriginalPayloadSize) */
+#define SMB_COMPRESS_HDR_LEN		16
+/* sizeof(smb2_compression_payload_hdr) - sizeof(OriginalPayloadSize) */
+#define SMB_COMPRESS_PAYLOAD_HDR_LEN	8
+#define SMB_COMPRESS_MIN_LEN		PAGE_SIZE
+
+#ifdef CONFIG_CIFS_COMPRESSION
+typedef int (*compress_send_fn)(struct TCP_Server_Info *, int, struct smb_rqst *);
+
+
+int smb_compress(struct TCP_Server_Info *server, struct smb_rqst *rq,
+		 compress_send_fn send_fn);
+bool should_compress(const struct cifs_tcon *tcon, const struct smb_rqst *rq);
+
+#else /* !CONFIG_CIFS_COMPRESSION */
+static inline int smb_compress(void *unused1, void *unused2, void *unused3)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline bool should_compress(void *unused1, void *unused2)
+{
+	return false;
+}
+
+#endif /* !CONFIG_CIFS_COMPRESSION */
+#endif /* _SMB_COMPRESS_H */